The Human Periallocortex: Layer Pattern in Presubiculum, Parasubiculum and Entorhinal Cortex. A Review

PubMed Central

Insausti, Ricardo; Muñoz-López, Mónica; Insausti, Ana M.; Artacho-Pérula, Emilio

2017-01-01

The cortical mantle is not homogeneous, so that three types of cortex can be distinguished: allocortex, periallocortex and isocortex. The main distinction among those three types is based on morphological differences, in particular the number of layers, overall organization, appearance, etc., as well as its connectivity. Additionally, in the phylogenetic scale, this classification is conserved among different mammals. The most primitive and simple cortex is the allocortex, which is characterized by the presence of three layers, with one cellular main layer; it is continued by the periallocortex, which presents six layers, although with enough differences in the layer pattern to separate three different fields: presubiculum (PrS), parasubiculum (PaS), and entorhinal cortex (EC). The closest part to the allocortex (represented by the subiculum) is the PrS, which shows outer (layers I–III) and inner (V–VI) principal layers (lamina principalis externa and lamina principalis interna), both separated by a cell poor band, parallel to the pial surface (layer IV or lamina dissecans). This layer organization is present throughout the anterior-posterior axis. The PaS continues the PrS, but its rostrocaudal extent is shorter than the PrS. The organization of the PaS shows the layer pattern more clearly than in the PrS. Up to six layers are recognizable in the PaS, with layer IV as lamina dissecans between superficial (layers I–III) and deep (V–VI) layers, as in the PrS. The EC presents even more clearly the layer pattern along both mediolateral and rostrocaudal extent. The layer pattern is a thick layer I, layer II in islands, layer III medium pyramids, layer IV as lamina dissecans (not present throughout the EC extent), layer V with dark and big pyramids and a multiform layer VI. The EC borders laterally the proisocortex (incomplete type of isocortex). Variations in the appearance of its layers justify the distinction of subfields in the EC, in particular in human and nonhuman primates. EC layers are not similar to those in the neocortex. The transition between the periallocortical EC and isocortex is not sharp, so that the proisocortex forms an intervening cortex, which fills the gap between the periallocortex and the isocortex. PMID:29046628

The Human Periallocortex: Layer Pattern in Presubiculum, Parasubiculum and Entorhinal Cortex. A Review.

PubMed

Insausti, Ricardo; Muñoz-López, Mónica; Insausti, Ana M; Artacho-Pérula, Emilio

2017-01-01

The cortical mantle is not homogeneous, so that three types of cortex can be distinguished: allocortex, periallocortex and isocortex. The main distinction among those three types is based on morphological differences, in particular the number of layers, overall organization, appearance, etc., as well as its connectivity. Additionally, in the phylogenetic scale, this classification is conserved among different mammals. The most primitive and simple cortex is the allocortex, which is characterized by the presence of three layers, with one cellular main layer; it is continued by the periallocortex, which presents six layers, although with enough differences in the layer pattern to separate three different fields: presubiculum (PrS), parasubiculum (PaS), and entorhinal cortex (EC). The closest part to the allocortex (represented by the subiculum) is the PrS, which shows outer (layers I-III) and inner (V-VI) principal layers ( lamina principalis externa and lamina principalis interna ), both separated by a cell poor band, parallel to the pial surface (layer IV or lamina dissecans ). This layer organization is present throughout the anterior-posterior axis. The PaS continues the PrS, but its rostrocaudal extent is shorter than the PrS. The organization of the PaS shows the layer pattern more clearly than in the PrS. Up to six layers are recognizable in the PaS, with layer IV as lamina dissecans between superficial (layers I-III) and deep (V-VI) layers, as in the PrS. The EC presents even more clearly the layer pattern along both mediolateral and rostrocaudal extent. The layer pattern is a thick layer I, layer II in islands, layer III medium pyramids, layer IV as lamina dissecans (not present throughout the EC extent), layer V with dark and big pyramids and a multiform layer VI. The EC borders laterally the proisocortex (incomplete type of isocortex). Variations in the appearance of its layers justify the distinction of subfields in the EC, in particular in human and nonhuman primates. EC layers are not similar to those in the neocortex. The transition between the periallocortical EC and isocortex is not sharp, so that the proisocortex forms an intervening cortex, which fills the gap between the periallocortex and the isocortex.

Sonic Hedgehog Expression in Corticofugal Projection Neurons Directs Cortical Microcircuit Formation

PubMed Central

Harwell, Corey C.; Parker, Philip R.L.; Gee, Steven M.; Okada, Ami; McConnell, Susan K.; Kreitzer, Anatol C.; Kriegstein, Arnold R.

2012-01-01

SUMMARY The precise connectivity of inputs and outputs is critical for cerebral cortex function; however, the cellular mechanisms that establish these connections are poorly understood. Here, we show that the secreted molecule Sonic Hedgehog (Shh) is involved in synapse formation of a specific cortical circuit. Shh is expressed in layer V corticofugal projection neurons and the Shh receptor, Brother of CDO (Boc), is expressed in local and callosal projection neurons of layer II/III that synapse onto the subcortical projection neurons. Layer V neurons of mice lacking functional Shh exhibit decreased synapses. Conversely, the loss of functional Boc leads to a reduction in the strength of synaptic connections onto layer Vb, but not layer II/III, pyramidal neurons. These results demonstrate that Shh is expressed in postsynaptic target cells while Boc is expressed in a complementary population of presynaptic input neurons, and they function to guide the formation of cortical microcircuitry. PMID:22445340

TRH regulates action potential shape in cerebral cortex pyramidal neurons.

PubMed

Rodríguez-Molina, Víctor; Patiño, Javier; Vargas, Yamili; Sánchez-Jaramillo, Edith; Joseph-Bravo, Patricia; Charli, Jean-Louis

2014-07-07

Thyrotropin releasing hormone (TRH) is a neuropeptide with a wide neural distribution and a variety of functions. It modulates neuronal electrophysiological properties, including resting membrane potential, as well as excitatory postsynaptic potential and spike frequencies. We explored, with whole-cell patch clamp, TRH effect on action potential shape in pyramidal neurons of the sensorimotor cortex. TRH reduced spike and after hyperpolarization amplitudes, and increased spike half-width. The effect varied with dose, time and cortical layer. In layer V, 0.5µM of TRH induced a small increase in spike half-width, while 1 and 5µM induced a strong but transient change in spike half-width, and amplitude; after hyperpolarization amplitude was modified at 5µM of TRH. Cortical layers III and VI neurons responded intensely to 0.5µM TRH; layer II neurons response was small. The effect of 1µM TRH on action potential shape in layer V neurons was blocked by G-protein inhibition. Inhibition of the activity of the TRH-degrading enzyme pyroglutamyl peptidase II (PPII) reproduced the effect of TRH, with enhanced spike half-width. Many cortical PPII mRNA+ cells were VGLUT1 mRNA+, and some GAD mRNA+. These data show that TRH regulates action potential shape in pyramidal cortical neurons, and are consistent with the hypothesis that PPII controls its action in this region. Copyright © 2014 Elsevier B.V. All rights reserved.

Developmental ethanol exposure alters the morphology of mouse prefrontal neurons in a layer-specific manner.

PubMed

Louth, Emma L; Luctkar, Hanna D; Heney, Kayla A; Bailey, Craig D C

2018-01-01

Chronic developmental exposure to ethanol can lead to a wide variety of teratogenic effects, which in humans are known as fetal alcohol spectrum disorders (FASD). Individuals affected by FASD may exhibit persistent impairments to cognitive functions such as learning, memory, and attention, which are highly dependent on medial prefrontal cortex (mPFC) circuitry. The objective of this study was to determine long-term effects of chronic developmental ethanol exposure on mPFC neuron morphology, in order to better-understand potential neuronal mechanisms underlying cognitive impairments associated with FASD. C57BL/6-strain mice were exposed to ethanol or an isocaloric/isovolumetric amount of sucrose (control) via oral gavage, administered both to the dam from gestational day 10-18 and directly to pups from postnatal day 4-14. Brains from male mice were collected at postnatal day 90 and neurons were stained using a modified Golgi-Cox method. Pyramidal neurons within layers II/III, V and VI of the mPFC were imaged, traced in three dimensions, and assessed using Sholl and branch structure analyses. Developmental ethanol exposure differentially impacted adult pyramidal neuron morphology depending on mPFC cortical layer. Neurons in layer II/III exhibited increased size and diameter of dendrite trees, whereas neurons in layer V were not affected. Layer VI neurons with long apical dendrites had trees with decreased diameter that extended farther from the soma, and layer VI neurons with short apical dendrite trees exhibited decreased tree size overall. These layer-specific alterations to mPFC neuron morphology may form a novel morphological mechanism underlying long-term mPFC dysfunction and resulting cognitive impairments in FASD. Copyright © 2017 Elsevier B.V. All rights reserved.

Cholinergic neurons and fibres in the rat visual cortex.

PubMed

Parnavelas, J G; Kelly, W; Franke, E; Eckenstein, F

1986-06-01

Choline acetyltransferase (ChAT), the acetylcholine synthesizing enzyme, was localized immunocytochemically in neurons and fibres in the rat visual cortex using a monoclonal antibody. ChAT-labelled cells were non-pyramidal neurons, primarily of the bipolar form, distributed in layers II through VI but concentrated in layers II & III. Their perikarya contained a large nucleus and a small amount of perinuclear cytoplasm. The somata and dendrites of all labelled cells received Gray's type I and type II synapses. ChAT-stained axons formed a dense and diffuse network throughout the visual cortex and particularly in layer V. Electron microscopy revealed that the great majority formed type II synaptic contacts with dendrites of various sizes, unlabelled non-pyramidal somata and, on a few occasions, with ChAT-labelled cells. However, a very small number of terminals appeared to form type I synaptic contacts. This study describes the morphological organization of the cholinergic system in the visual cortex, the function of which has been under extensive investigation.

Callosal responses in a retrosplenial column.

PubMed

Sempere-Ferràndez, Alejandro; Andrés-Bayón, Belén; Geijo-Barrientos, Emilio

2018-04-01

The axons forming the corpus callosum sustain the interhemispheric communication across homotopic cortical areas. We have studied how neurons throughout the columnar extension of the retrosplenial cortex integrate the contralateral input from callosal projecting neurons in cortical slices. Our results show that pyramidal neurons in layers 2/3 and the large, thick-tufted pyramidal neurons in layer 5B showed larger excitatory callosal responses than layer 5A and layer 5B thin-tufted pyramidal neurons, while layer 6 remained silent to this input. Feed-forward inhibitory currents generated by fast spiking, parvalbumin expressing  interneurons recruited by callosal axons mimicked the response size distribution of excitatory responses across pyramidal subtypes, being larger in those of superficial layers and in the layer 5B thick-tufted pyramidal cells. Overall, the combination of the excitatory and inhibitory currents evoked by callosal input had a strong and opposed effect in different layers of the cortex; while layer 2/3 pyramidal neurons were powerfully inhibited, the thick-tufted but not thin-tufted pyramidal neurons in layer 5 were strongly recruited. We believe that these results will help to understand the functional role of callosal connections in physiology and disease.

Sonic hedgehog expression in corticofugal projection neurons directs cortical microcircuit formation.

PubMed

Harwell, Corey C; Parker, Philip R L; Gee, Steven M; Okada, Ami; McConnell, Susan K; Kreitzer, Anatol C; Kriegstein, Arnold R

2012-03-22

The precise connectivity of inputs and outputs is critical for cerebral cortex function; however, the cellular mechanisms that establish these connections are poorly understood. Here, we show that the secreted molecule Sonic Hedgehog (Shh) is involved in synapse formation of a specific cortical circuit. Shh is expressed in layer V corticofugal projection neurons and the Shh receptor, Brother of CDO (Boc), is expressed in local and callosal projection neurons of layer II/III that synapse onto the subcortical projection neurons. Layer V neurons of mice lacking functional Shh exhibit decreased synapses. Conversely, the loss of functional Boc leads to a reduction in the strength of synaptic connections onto layer Vb, but not layer II/III, pyramidal neurons. These results demonstrate that Shh is expressed in postsynaptic target cells while Boc is expressed in a complementary population of presynaptic input neurons, and they function to guide the formation of cortical microcircuitry. Copyright © 2012 Elsevier Inc. All rights reserved.

Efficacy and connectivity of intracolumnar pairs of layer 2/3 pyramidal cells in the barrel cortex of juvenile rats

PubMed Central

Feldmeyer, Dirk; Lübke, Joachim; Sakmann, Bert

2006-01-01

Synaptically coupled layer 2/3 (L2/3) pyramidal neurones located above the same layer 4 barrel (‘barrel-related’) were investigated using dual whole-cell voltage recordings in acute slices of rat somatosensory cortex. Recordings were followed by reconstructions of biocytin-filled neurones. The onset latency of unitary EPSPs was 1.1 ± 0.4 ms, the 20–80% rise time was 0.7 ± 0.2 ms, the average amplitude was 1.0 ± 0.7 mV and the decay time constant was 15.7 ± 4.5 ms. The coefficient of variation (c.v.) of unitary EPSP amplitudes decreased with increasing EPSP peak and was 0.33 ± 0.18. Bursts of APs in the presynaptic pyramidal cell resulted in EPSPs that, over a wide range of frequencies (5–100 Hz), displayed amplitude depression. Anatomically the barrel-related pyramidal cells in the lower half of layer 2/3 have a long apical dendrite with a small terminal tuft, while pyramidal cells in the upper half of layer 2/3 have shorter and often more ‘irregularly’ shaped apical dendrites that branch profusely in layer 1. The number of putative excitatory synaptic contacts established by the axonal collaterals of a L2/3 pyramidal cell with a postsynaptic pyramidal cell in the same column varied between 2 and 4, with an average of 2.8 ± 0.7 (n = 8 pairs). Synaptic contacts were established predominantly on the basal dendrites at a mean geometric distance of 91 ± 47 μm from the pyramidal cell soma. L2/3-to-L2/3 connections formed a blob-like innervation domain containing 2.8 mm of the presynaptic axon collaterals with a bouton density of 0.3 boutons per μm axon. Within the supragranular layers of its home column a single L2/3 pyramidal cell established about 900 boutons suggesting that 270 pyramidal cells in layer 2/3 are innervated by an individual pyramidal cell. In turn, a single pyramidal cell received synaptic inputs from 270 other L2/3 pyramidal cells. The innervation domain of L2/3-to-L2/3 connections superimposes almost exactly with that of L4-to-L2/3 connections. This suggests that synchronous feed-forward excitation of L2/3 pyramidal cells arriving from layer 4 could be potentially amplified in layer 2/3 by feedback excitation within a column and then relayed to the neighbouring columns. PMID:16793907

Molecular and Electrophysiological Characterization of GABAergic Interneurons Expressing the Transcription Factor COUP-TFII in the Adult Human Temporal Cortex

PubMed Central

Varga, Csaba; Tamas, Gabor; Barzo, Pal; Olah, Szabolcs; Somogyi, Peter

2015-01-01

Transcription factors contribute to the differentiation of cortical neurons, orchestrate specific interneuronal circuits, and define synaptic relationships. We have investigated neurons expressing chicken ovalbumin upstream promoter transcription factor II (COUP-TFII), which plays a role in the migration of GABAergic neurons. Whole-cell, patch-clamp recording in vitro combined with colocalization of molecular cell markers in the adult cortex differentiates distinct interneurons. The majority of strongly COUP-TFII-expressing neurons were in layers I–III. Most calretinin (CR) and/or cholecystokinin- (CCK) and/or reelin-positive interneurons were also COUP-TFII-positive. CR-, CCK-, or reelin-positive neurons formed 80%, 20%, or 17% of COUP-TFII-positive interneurons, respectively. About half of COUP-TFII-/CCK-positive interneurons were CR-positive, a quarter of them reelin-positive, but none expressed both. Interneurons positive for COUP-TFII fired irregular, accommodating and adapting trains of action potentials (APs) and innervated mostly small dendritic shafts and rarely spines or somata. Paired recording showed that a calretinin-/COUP-TFII-positive interneuron elicited inhibitory postsynaptic potentials (IPSPs) in a reciprocally connected pyramidal cell. Calbindin, somatostatin, or parvalbumin-immunoreactive interneurons and most pyramidal cells express no immunohistochemically detectable COUP-TFII. In layers V and VI, some pyramidal cells expressed a low level of COUP-TFII in the nucleus. In conclusion, COUP-TFII is expressed in a diverse subset of GABAergic interneurons predominantly innervating small dendritic shafts originating from both interneurons and pyramidal cells. PMID:25787832

Pressure-Driven Spin Crossover Involving Polyhedral Transformation in Layered Perovskite Cobalt Oxyfluoride

PubMed Central

Tsujimoto, Yoshihiro; Nakano, Satoshi; Ishimatsu, Naoki; Mizumaki, Masaichiro; Kawamura, Naomi; Kawakami, Takateru; Matsushita, Yoshitaka; Yamaura, Kazunari

2016-01-01

We report a novel pressure-driven spin crossover in layered cobalt oxyfluoride Sr2CoO3F with a distorted CoO5 square pyramid loosely bound with a fluoride ion. Upon increasing pressure, the spin state of the Co(III) cation gradually changes from a high spin state (S = 2) to a low spin state (S = 0) accompanied by a anomalously large volume contraction (bulk modulus, 76.8(5) GPa). The spin state change occurs on the CoO5 pyramid in a wide pressure range, but the concomitant gradual shrinkage of the Co–F bond length with pressure gives rise to a polyhedral transformation to the CoO5F octahedron without a structural phase transition, leading to the full conversion to the LS state at 12 GPa. The present results provide new effective strategy to fine-tune electronic properties of mixed anion systems by controlling the covalency in metal-ligand bonds under pressure. PMID:27805031

Mitochondrial Damage: A Diagnostic and Metabolic Approach in Traumatic Brain Injury and Post-Traumatic Disorder

DTIC Science & Technology

2013-01-29

Scanning Confocal Microscope (Zeiss- Pascal) using 20x obj. and edited using Zeiss Image Examiner Ver 5.0. The iso-cortical pyramidal layers 1 and 2 are...NeuN immunoreactivity is seen in the neuronal cytoplasm and especially apical dendrites of pyramidal neurons (white arrows), which facilitates the...identification of the pyramidal cell morphology in the outer pyramidal cell layer of neo-cortex (see picture A, depicted as py). Cortical Pyramidal

Distinctive transcriptome alterations of prefrontal pyramidal neurons in schizophrenia and schizoaffective disorder

PubMed Central

Arion, Dominique; Corradi, John P.; Tang, Shaowu; Datta, Dibyadeep; Boothe, Franklyn; He, Aiqing; Cacace, Angela M.; Zaczek, Robert; Albright, Charles F.; Tseng, George; Lewis, David A.

2014-01-01

Schizophrenia is associated with alterations in working memory that reflect dysfunction of dorsolateral prefrontal cortex (DLPFC) circuitry. Working memory depends on the activity of excitatory pyramidal cells in DLPFC layer 3, and to a lesser extent in layer 5. Although many studies have profiled gene expression in DLPFC gray matter in schizophrenia, little is known about cell type-specific transcript expression in these two populations of pyramidal cells. We hypothesized that interrogating gene expression specifically in DLPFC layer 3 or 5 pyramidal cells would reveal new and/or more robust schizophrenia-associated differences that would provide new insights into the nature of pyramidal cell dysfunction in the illness. We also sought to determine the impact of other variables, such as a diagnosis of schizoaffective disorder or medication use at time of death, on the patterns of gene expression in pyramidal neurons. Individual pyramidal cells in DLPFC layers 3 or 5 were captured by laser microdissection from 36 subjects with schizophrenia or schizoaffective disorder and matched normal comparison subjects. The mRNA from cell collections was subjected to transcriptome profiling by microarray followed by qPCR validation. Expression of genes involved in mitochondrial (MT) or ubiquitin-proteasome system (UPS) functions were markedly down-regulated in the patient group (p values for MT-related and UPS-related pathways were <10−7 and <10−5 respectively). MT-related gene alterations were more prominent in layer 3 pyramidal cells, whereas UPS-related gene alterations were more prominent in layer 5 pyramidal cells. Many of these alterations were not present, or found to a lesser degree, in samples of DLPFC gray matter from the same subjects, suggesting that they are pyramidal cell-specific. Furthermore, these findings principally reflected alterations in the schizophrenia subjects, were not present or present to a lesser degree in the schizoaffective disorder subjects (diagnosis of schizoaffective disorder was the most significant covariate, p<10−6), and were not attributable to factors frequently comorbid with schizophrenia. In summary, our findings reveal expression deficits in MT- and UPS-related genes specific to layer 3 and/or layer 5 pyramidal cells in the DLPFC of schizophrenia subjects. These cell type-specific transcriptome signatures are not characteristic of schizoaffective disorder, providing a potential molecular-cellular basis of differences in clinical phenotypes. PMID:25560755

Distinctive transcriptome alterations of prefrontal pyramidal neurons in schizophrenia and schizoaffective disorder.

PubMed

Arion, D; Corradi, J P; Tang, S; Datta, D; Boothe, F; He, A; Cacace, A M; Zaczek, R; Albright, C F; Tseng, G; Lewis, D A

2015-11-01

Schizophrenia is associated with alterations in working memory that reflect dysfunction of dorsolateral prefrontal cortex (DLPFC) circuitry. Working memory depends on the activity of excitatory pyramidal cells in DLPFC layer 3 and, to a lesser extent, in layer 5. Although many studies have profiled gene expression in DLPFC gray matter in schizophrenia, little is known about cell-type-specific transcript expression in these two populations of pyramidal cells. We hypothesized that interrogating gene expression, specifically in DLPFC layer 3 or 5 pyramidal cells, would reveal new and/or more robust schizophrenia-associated differences that would provide new insights into the nature of pyramidal cell dysfunction in the illness. We also sought to determine the impact of other variables, such as a diagnosis of schizoaffective disorder or medication use at the time of death, on the patterns of gene expression in pyramidal neurons. Individual pyramidal cells in DLPFC layers 3 or 5 were captured by laser microdissection from 36 subjects with schizophrenia or schizoaffective disorder and matched normal comparison subjects. The mRNA from cell collections was subjected to transcriptome profiling by microarray followed by quantitative PCR validation. Expression of genes involved in mitochondrial (MT) or ubiquitin-proteasome system (UPS) functions were markedly downregulated in the patient group (P-values for MT-related and UPS-related pathways were <10(-7) and <10(-5), respectively). MT-related gene alterations were more prominent in layer 3 pyramidal cells, whereas UPS-related gene alterations were more prominent in layer 5 pyramidal cells. Many of these alterations were not present, or found to a lesser degree, in samples of DLPFC gray matter from the same subjects, suggesting that they are pyramidal cell specific. Furthermore, these findings principally reflected alterations in the schizophrenia subjects were not present or present to a lesser degree in the schizoaffective disorder subjects (diagnosis of schizoaffective disorder was the most significant covariate, P<10(-6)) and were not attributable to factors frequently comorbid with schizophrenia. In summary, our findings reveal expression deficits in MT- and UPS-related genes specific to layer 3 and/or layer 5 pyramidal cells in the DLPFC of schizophrenia subjects. These cell type-specific transcriptome signatures are not characteristic of schizoaffective disorder, providing a potential molecular-cellular basis of differences in clinical phenotypes.

Dendritic branching angles of pyramidal cells across layers of the juvenile rat somatosensory cortex.

PubMed

Leguey, Ignacio; Bielza, Concha; Larrañaga, Pedro; Kastanauskaite, Asta; Rojo, Concepción; Benavides-Piccione, Ruth; DeFelipe, Javier

2016-09-01

The characterization of the structural design of cortical microcircuits is essential for understanding how they contribute to function in both health and disease. Since pyramidal neurons represent the most abundant neuronal type and their dendritic spines constitute the major postsynaptic elements of cortical excitatory synapses, our understanding of the synaptic organization of the neocortex largely depends on the available knowledge regarding the structure of pyramidal cells. Previous studies have identified several apparently common rules in dendritic geometry. We study the dendritic branching angles of pyramidal cells across layers to further shed light on the principles that determine the geometric shapes of these cells. We find that the dendritic branching angles of pyramidal cells from layers II-VI of the juvenile rat somatosensory cortex suggest common design principles, despite the particular morphological and functional features that are characteristic of pyramidal cells in each cortical layer. J. Comp. Neurol. 524:2567-2576, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Neocortical layers I and II of the hedgehog (Erinaceus europaeus). I. Intrinsic organization.

PubMed

Valverde, F; Facal-Valverde, M V

1986-01-01

The intrinsic organization and interlaminar connections in neocortical layers I and II have been studied in adult hedgehogs (Erinaceus europaeus) using the Golgi method. Layer I contains a dense plexus of horizontal fibers, the terminal dendritic bouquets of pyramidal cells of layer II and of underlying layers, and varieties of intrinsic neurons. Four main types of cells were found in layer I. Small horizontal cells represent most probably persisting foetal horizontal cells described for other mammals. Large horizontal cells, tufted cells, and spinous horizontal cells were also found in this layer. Layer II contains primitive pyramidal cells representing the most outstanding feature of the neocortex of the hedgehog. Most pyramidal cells in layer II have two, three or more apical dendrites, richly covered by spines predominating over the basal dendrites. These cells resemble pyramidal cells found in the piriform cortex, hippocampus and other olfactory areas. It is suggested that the presence of these neurons reflects the retention of a primitive character in neocortical evolution. Cells with intrinsic axons were found among pyramidal cells in layer II. These have smooth dendrites penetrating layer I and local axons forming extremely complex terminal arborizations around the bodies and proximal dendritic portions of pyramidal cells. They most probably effect numerous axo-somatic contacts resembling basket cells. The similarity of some axonal terminals with the chandelier type of axonal arborization is discussed. Other varieties of cells located in deep cortical layers and having ascending axons for layers I and II were also studied. It is concluded that the two first neocortical layers represent a level of important integration in this primitive mammal.

Layer 5 Pyramidal Neurons' Dendritic Remodeling and Increased Microglial Density in Primary Motor Cortex in a Murine Model of Facial Paralysis

PubMed Central

Urrego, Diana; Troncoso, Julieta; Múnera, Alejandro

2015-01-01

This work was aimed at characterizing structural changes in primary motor cortex layer 5 pyramidal neurons and their relationship with microglial density induced by facial nerve lesion using a murine facial paralysis model. Adult transgenic mice, expressing green fluorescent protein in microglia and yellow fluorescent protein in projecting neurons, were submitted to either unilateral section of the facial nerve or sham surgery. Injured animals were sacrificed either 1 or 3weeks after surgery. Two-photon excitation microscopy was then used for evaluating both layer 5 pyramidal neurons and microglia in vibrissal primary motor cortex (vM1). It was found that facial nerve lesion induced long-lasting changes in the dendritic morphology of vM1 layer 5 pyramidal neurons and in their surrounding microglia. Dendritic arborization of the pyramidal cells underwent overall shrinkage. Apical dendrites suffered transient shortening while basal dendrites displayed sustained shortening. Moreover, dendrites suffered transient spine pruning. Significantly higher microglial cell density was found surrounding vM1 layer 5 pyramidal neurons after facial nerve lesion with morphological bias towards the activated phenotype. These results suggest that facial nerve lesions elicit active dendrite remodeling due to pyramidal neuron and microglia interaction, which could be the pathophysiological underpinning of some neuropathic motor sequelae in humans. PMID:26064916

Alterations of cortical pyramidal neurons in mice lacking high-affinity nicotinic receptors

PubMed Central

Ballesteros-Yáñez, Inmaculada; Benavides-Piccione, Ruth; Bourgeois, Jean-Pierre; Changeux, Jean-Pierre; DeFelipe, Javier

2010-01-01

The neuronal nicotinic acetylcholine receptors (nAChRs) are allosteric membrane proteins involved in multiple cognitive processes, including attention, learning, and memory. The most abundant form of heterooligomeric nAChRs in the brain contains the β2- and α4- subunits and binds nicotinic agonists with high affinity. In the present study, we investigated in the mouse the consequences of the deletion of one of the nAChR components: the β2-subunit (β2−/−) on the microanatomy of cortical pyramidal cells. Using an intracellular injection method, complete basal dendritic arbors of 650 layer III pyramidal neurons were sampled from seven cortical fields, including primary sensory, motor, and associational areas, in both β2−/− and WT animals. We observed that the pyramidal cell phenotype shows significant quantitative differences among different cortical areas in mutant and WT mice. In WT mice, the density of dendritic spines was rather similar in all cortical fields, except in the prelimbic/infralimbic cortex, where it was significantly higher. In the absence of the β2-subunit, the most significant reduction in the density of spines took place in this high-order associational field. Our data suggest that the β2-subunit is involved in the dendritic morphogenesis of pyramidal neurons and, in particular, in the circuits that contribute to the high-order functional connectivity of the cerebral cortex. PMID:20534523

Binding and segmentation via a neural mass model trained with Hebbian and anti-Hebbian mechanisms.

PubMed

Cona, Filippo; Zavaglia, Melissa; Ursino, Mauro

2012-04-01

Synchronization of neural activity in the gamma band, modulated by a slower theta rhythm, is assumed to play a significant role in binding and segmentation of multiple objects. In the present work, a recent neural mass model of a single cortical column is used to analyze the synaptic mechanisms which can warrant synchronization and desynchronization of cortical columns, during an autoassociation memory task. The model considers two distinct layers communicating via feedforward connections. The first layer receives the external input and works as an autoassociative network in the theta band, to recover a previously memorized object from incomplete information. The second realizes segmentation of different objects in the gamma band. To this end, units within both layers are connected with synapses trained on the basis of previous experience to store objects. The main model assumptions are: (i) recovery of incomplete objects is realized by excitatory synapses from pyramidal to pyramidal neurons in the same object; (ii) binding in the gamma range is realized by excitatory synapses from pyramidal neurons to fast inhibitory interneurons in the same object. These synapses (both at points i and ii) have a few ms dynamics and are trained with a Hebbian mechanism. (iii) Segmentation is realized with faster AMPA synapses, with rise times smaller than 1 ms, trained with an anti-Hebbian mechanism. Results show that the model, with the previous assumptions, can correctly reconstruct and segment three simultaneous objects, starting from incomplete knowledge. Segmentation of more objects is possible but requires an increased ratio between the theta and gamma periods.

Hydrocephalus compacted cortex and hippocampus and altered their output neurons in association with spatial learning and memory deficits in rats.

PubMed

Chen, Li-Jin; Wang, Yueh-Jan; Chen, Jeng-Rung; Tseng, Guo-Fang

2017-07-01

Hydrocephalus is a common neurological disorder in children characterized by abnormal dilation of cerebral ventricles as a result of the impairment of cerebrospinal fluid flow or absorption. Clinical presentation of hydrocephalus varies with chronicity and often shows cognitive dysfunction. Here we used a kaolin-induction method in rats and studied the effects of hydrocephalus on cerebral cortex and hippocampus, the two regions highly related to cognition. Hydrocephalus impaired rats' performance in Morris water maze task. Serial three-dimensional reconstruction from sections of the whole brain freshly froze in situ with skull shows that the volumes of both structures were reduced. Morphologically, pyramidal neurons of the somatosensory cortex and hippocampus appear to be distorted. Intracellular dye injection and subsequent three-dimensional reconstruction and analyses revealed that the dendritic arbors of layer III and V cortical pyramid neurons were reduced. The total dendritic length of CA1, but not CA3, pyramidal neurons was also reduced. Dendritic spine densities on both cortical and hippocampal pyramidal neurons were decreased, consistent with our concomitant findings that the expressions of both synaptophysin and postsynaptic density protein 95 were reduced. These cortical and hippocampal changes suggest reductions of excitatory connectivity, which could underlie the learning and memory deficits in hydrocephalus. © 2016 International Society of Neuropathology.

Radiocarbon Ages and Environments of Deposition of the Wono and Trego Hot Springs Tephra Layers in the Pyramid Lake Subbasin, Nevada

USGS Publications Warehouse

Benson, L.V.; Smoot, J.P.; Kashgarian, Michaele; Sarna-Wojcicki, A.; Burdett, J.W.

1997-01-01

Uncalibrated radiocarbon data from core PLC92B taken from Wizards Cove in the Pyramid Lake subbasin indicate that the Trego Hot Springs and Wono tephra layers were deposited 23,200 ?? 300 and 27,300 ??300 14C yr B.P. (uncorrected for reservoir effect). Sedimentological data from sites in the Pyramid Lake and Smoke Creek-Black Rock Desert subbasins indicate that the Trego Hot Springs tephra layer was deposited during a relatively dry period when Pyramid Lake was at or below its spill point (1177 m) to the Winnemucca Lake subbasin. The Wono tephra layer was deposited when lake depth was controlled by spill across Emerson Pass sill (1207 m) to the Smoke Creek-Black Rock Desert subbasin. 18O data from core PLC92B also support the concept that the Trego Hot Springs tephra fell into a relatively shallow Pyramid Lake and that the Wono tephra fell into a deeper spilling lake. ?? 1997 University of Washington.

Pyramid image codes

NASA Technical Reports Server (NTRS)

Watson, Andrew B.

1990-01-01

All vision systems, both human and machine, transform the spatial image into a coded representation. Particular codes may be optimized for efficiency or to extract useful image features. Researchers explored image codes based on primary visual cortex in man and other primates. Understanding these codes will advance the art in image coding, autonomous vision, and computational human factors. In cortex, imagery is coded by features that vary in size, orientation, and position. Researchers have devised a mathematical model of this transformation, called the Hexagonal oriented Orthogonal quadrature Pyramid (HOP). In a pyramid code, features are segregated by size into layers, with fewer features in the layers devoted to large features. Pyramid schemes provide scale invariance, and are useful for coarse-to-fine searching and for progressive transmission of images. The HOP Pyramid is novel in three respects: (1) it uses a hexagonal pixel lattice, (2) it uses oriented features, and (3) it accurately models most of the prominent aspects of primary visual cortex. The transform uses seven basic features (kernels), which may be regarded as three oriented edges, three oriented bars, and one non-oriented blob. Application of these kernels to non-overlapping seven-pixel neighborhoods yields six oriented, high-pass pyramid layers, and one low-pass (blob) layer.

On atomic structure of Ge huts growing on the Ge/Si(001) wetting layer

NASA Astrophysics Data System (ADS)

Arapkina, Larisa V.; Yuryev, Vladimir A.

2013-09-01

Structural models of growing Ge hut clusters—pyramids and wedges—are proposed on the basis of data of recent STM investigations of nucleation and growth of Ge huts on the Si(001) surface in the process of molecular beam epitaxy. It is shown that extension of a hut base along ⟨110⟩ directions goes non-uniformly during the cluster growth regardless of its shape. Growing pyramids, starting from the second monolayer, pass through cyclic formation of slightly asymmetrical and symmetrical clusters, with symmetrical ones appearing after addition of every fourth monolayer. We suppose that pyramids of symmetrical configurations composed by 2, 6, 10, etc., monolayers over the wetting layer are more stable than asymmetrical ones. This might explain less stability of pyramids in comparison with wedges in dense arrays forming at low temperatures of Ge deposition. Possible nucleation processes of pyramids and wedges on wetting layer patches from identical embryos composed by 8 dimers through formation of 1 monolayer high 16-dimer nuclei different only in their symmetry is discussed. Schematics of these processes are presented. It is concluded from precise STM measurements that top layers of wetting layer patches are relaxed when huts nucleate on them.

On atomic structure of Ge huts growing on the Ge/Si(001) wetting layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arapkina, Larisa V.; Yuryev, Vladimir A.

Structural models of growing Ge hut clusters—pyramids and wedges—are proposed on the basis of data of recent STM investigations of nucleation and growth of Ge huts on the Si(001) surface in the process of molecular beam epitaxy. It is shown that extension of a hut base along <110> directions goes non-uniformly during the cluster growth regardless of its shape. Growing pyramids, starting from the second monolayer, pass through cyclic formation of slightly asymmetrical and symmetrical clusters, with symmetrical ones appearing after addition of every fourth monolayer. We suppose that pyramids of symmetrical configurations composed by 2, 6, 10, etc., monolayersmore » over the wetting layer are more stable than asymmetrical ones. This might explain less stability of pyramids in comparison with wedges in dense arrays forming at low temperatures of Ge deposition. Possible nucleation processes of pyramids and wedges on wetting layer patches from identical embryos composed by 8 dimers through formation of 1 monolayer high 16-dimer nuclei different only in their symmetry is discussed. Schematics of these processes are presented. It is concluded from precise STM measurements that top layers of wetting layer patches are relaxed when huts nucleate on them.« less

A Layer-specific Corticofugal Input to the Mouse Superior Colliculus.

PubMed

Zurita, Hector; Rock, Crystal; Perkins, Jessica; Apicella, Alfonso Junior

2017-07-05

In the auditory cortex (AC), corticofugal projections arise from each level of the auditory system and are considered to provide feedback "loops" important to modulate the flow of ascending information. It is well established that the cortex can influence the response of neurons in the superior colliculus (SC) via descending corticofugal projections. However, little is known about the relative contribution of different pyramidal neurons to these projections in the SC. We addressed this question by taking advantage of anterograde and retrograde neuronal tracing to directly examine the laminar distribution, long-range projections, and electrophysiological properties of pyramidal neurons projecting from the AC to the SC of the mouse brain. Here we show that layer 5 cortico-superior-collicular pyramidal neurons act as bandpass filters, resonating with a broad peak at ∼3 Hz, whereas layer 6 neurons act as low-pass filters. The dissimilar subthreshold properties of layer 5 and layer 6 cortico-superior-collicular pyramidal neurons can be described by differences in the hyperpolarization-activated cyclic nucleotide-gated cation h-current (Ih). Ih also reduced the summation of short trains of artificial excitatory postsynaptic potentials injected at the soma of layer 5, but not layer 6, cortico-superior-collicular pyramidal neurons, indicating a differential dampening effect of Ih on these neurons. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Post-Inhibitory Rebound Spikes in Rat Medial Entorhinal Layer II/III Principal Cells: In Vivo, In Vitro, and Computational Modeling Characterization

PubMed Central

Ferrante, Michele; Shay, Christopher F.; Tsuno, Yusuke; William Chapman, G.; Hasselmo, Michael E.

2017-01-01

Abstract Medial entorhinal cortex Layer-II stellate cells (mEC-LII-SCs) primarily interact via inhibitory interneurons. This suggests the presence of alternative mechanisms other than excitatory synaptic inputs for triggering action potentials (APs) in stellate cells during spatial navigation. Our intracellular recordings show that the hyperpolarization-activated cation current (Ih) allows post-inhibitory-rebound spikes (PIRS) in mEC-LII-SCs. In vivo, strong inhibitory-post-synaptic potentials immediately preceded most APs shortening their delay and enhancing excitability. In vitro experiments showed that inhibition initiated spikes more effectively than excitation and that more dorsal mEC-LII-SCs produced faster and more synchronous spikes. In contrast, PIRS in Layer-II/III pyramidal cells were harder to evoke, voltage-independent, and slower in dorsal mEC. In computational simulations, mEC-LII-SCs morphology and Ih homeostatically regulated the dorso-ventral differences in PIRS timing and most dendrites generated PIRS with a narrow range of stimulus amplitudes. These results suggest inhibitory inputs could mediate the emergence of grid cell firing in a neuronal network. PMID:26965902

The Effect of Single Pyramidal Neuron Firing Within Layer 2/3 and Layer 4 in Mouse V1.

PubMed

Meyer, Jochen F; Golshani, Peyman; Smirnakis, Stelios M

2018-01-01

The influence of cortical cell spiking activity on nearby cells has been studied extensively in vitro . Less is known, however, about the impact of single cell firing on local cortical networks in vivo . In a pioneering study, Kwan and Dan (Kwan and Dan, 2012) reported that in mouse layer 2/3 (L2/3), under anesthesia , stimulating a single pyramidal cell recruits ~2.1% of neighboring units. Here we employ two-photon calcium imaging in layer 2/3 of mouse V1, in conjunction with single-cell patch clamp stimulation in layer 2/3 or layer 4, to probe, in both the awake and lightly anesthetized states , how (i) activating single L2/3 pyramidal neurons recruits neighboring units within L2/3 and from layer 4 (L4) to L2/3, and whether (ii) activating single pyramidal neurons changes population activity in local circuit. To do this, it was essential to develop an algorithm capable of quantifying how sensitive the calcium signal is at detecting effectively recruited units ("followers"). This algorithm allowed us to estimate the chance of detecting a follower as a function of the probability that an epoch of stimulation elicits one extra action potential (AP) in the follower cell. Using this approach, we found only a small fraction (<0.75%) of L2/3 cells to be significantly activated within a radius of ~200 μm from a stimulated neighboring L2/3 pyramidal cell. This fraction did not change significantly in the awake vs. the lightly anesthetized state, nor when stimulating L2/3 vs. underlying L4 pyramidal neurons. These numbers are in general agreement with, though lower than, the percentage of neighboring cells (2.1% pyramidal cells and interneurons combined) reported by Kwan and Dan to be activated upon stimulating single L2/3 pyramidal neurons under anesthesia (Kwan and Dan, 2012). Interestingly, despite the small number of individual units found to be reliably driven, we did observe a modest but significant elevation in aggregate population responses compared to sham stimulation. This underscores the distributed impact that single cell stimulation has on neighboring microcircuit responses, revealing only a small minority of relatively strongly connected partners. Patch-clamp stimulation in conjunction with 2-photon imaging shows that activating single layer-2/3 or layer-4 pyramidal neurons produces few (<1% of local units) reliable single-cell followers in L2/3 of mouse area V1, either under light anesthesia or in quiet wakefulness: instead, single cell stimulation was found to elevate aggregate population activity in a weak but highly distributed fashion.

Attentional control of associative learning--a possible role of the central cholinergic system.

PubMed

Pauli, Wolfgang M; O'Reilly, Randall C

2008-04-02

How does attention interact with learning? Kruschke [Kruschke, J.K. (2001). Toward a unified Model of Attention in Associative Learning. J. Math. Psychol. 45, 812-863.] proposed a model (EXIT) that captures Mackintosh's [Mackintosh, N.J. (1975). A theory of attention: Variations in the associability of stimuli with reinforcement. Psychological Review, 82(4), 276-298.] framework for attentional modulation of associative learning. We developed a computational model that showed analogous interactions between selective attention and associative learning, but is significantly simplified and, in contrast to EXIT, is motivated by neurophysiological findings. Competition among input representations in the internal representation layer, which increases the contrast between stimuli, is critical for simulating these interactions in human behavior. Furthermore, this competition is modulated in a way that might be consistent with the phasic activation of the central cholinergic system, which modulates activity in sensory cortices. Specifically, phasic increases in acetylcholine can cause increased excitability of both pyramidal excitatory neurons in cortical layers II/III and cortical GABAergic inhibitory interneurons targeting the same pyramidal neurons. These effects result in increased attentional contrast in our model. This model thus represents an initial attempt to link human attentional learning data with underlying neural substrates.

Attentional control of associative learning—A possible role of the central cholinergic system

PubMed Central

Pauli, Wolfgang M.; O'Reilly, Randall C.

2010-01-01

How does attention interact with learning? Kruschke [Kruschke, J.K. (2001). Toward a unified Model of Attention in Associative Learning. J. Math. Psychol. 45, 812–863.] proposed a model (EXIT) that captures Mackintosh's [Mackintosh, N.J. (1975). A theory of attention: Variations in the associability of stimuli with reinforcement. Psychological Review, 82(4), 276–298.] framework for attentional modulation of associative learning. We developed a computational model that showed analogous interactions between selective attention and associative learning, but is significantly simplified and, in contrast to EXIT, is motivated by neurophysiological findings. Competition among input representations in the internal representation layer, which increases the contrast between stimuli, is critical for simulating these interactions in human behavior. Furthermore, this competition is modulated in a way that might be consistent with the phasic activation of the central cholinergic system, which modulates activity in sensory cortices. Specifically, phasic increases in acetylcholine can cause increased excitability of both pyramidal excitatory neurons in cortical layers II/III and cortical GABAergic inhibitory interneurons targeting the same pyramidal neurons. These effects result in increased attentional contrast in our model. This model thus represents an initial attempt to link human attentional learning data with underlying neural substrates. PMID:17870060

Ultrasonographic Diagnosis of Cirrhosis Based on Preprocessing Using Pyramid Recurrent Neural Network

NASA Astrophysics Data System (ADS)

Lu, Jianming; Liu, Jiang; Zhao, Xueqin; Yahagi, Takashi

In this paper, a pyramid recurrent neural network is applied to characterize the hepatic parenchymal diseases in ultrasonic B-scan texture. The cirrhotic parenchymal diseases are classified into 4 types according to the size of hypoechoic nodular lesions. The B-mode patterns are wavelet transformed , and then the compressed data are feed into a pyramid neural network to diagnose the type of cirrhotic diseases. Compared with the 3-layer neural networks, the performance of the proposed pyramid recurrent neural network is improved by utilizing the lower layer effectively. The simulation result shows that the proposed system is suitable for diagnosis of cirrhosis diseases.

Enhanced photovoltaic performance of inverted pyramid-based nanostructured black-silicon solar cells passivated by an atomic-layer-deposited Al2O3 layer.

PubMed

Chen, Hong-Yan; Lu, Hong-Liang; Ren, Qing-Hua; Zhang, Yuan; Yang, Xiao-Feng; Ding, Shi-Jin; Zhang, David Wei

2015-10-07

Inverted pyramid-based nanostructured black-silicon (BS) solar cells with an Al2O3 passivation layer grown by atomic layer deposition (ALD) have been demonstrated. A multi-scale textured BS surface combining silicon nanowires (SiNWs) and inverted pyramids was obtained for the first time by lithography and metal catalyzed wet etching. The reflectance of the as-prepared BS surface was about 2% lower than that of the more commonly reported upright pyramid-based SiNW BS surface over the whole of the visible light spectrum, which led to a 1.7 mA cm(-2) increase in short circuit current density. Moreover, the as-prepared solar cells were further passivated by an ALD-Al2O3 layer. The effect of annealing temperature on the photovoltaic performance of the solar cells was investigated. It was found that the values of all solar cell parameters including short circuit current, open circuit voltage, and fill factor exhibit a further increase under an optimized annealing temperature. Minority carrier lifetime measurements indicate that the enhanced cell performance is due to the improved passivation quality of the Al2O3 layer after thermal annealing treatments. By combining these two refinements, the optimized SiNW BS solar cells achieved a maximum conversion efficiency enhancement of 7.6% compared to the cells with an upright pyramid-based SiNWs surface and conventional SiNx passivation.

Evaluation of nature and extent of injuries during Dahihandi festival.

PubMed

Nemade, P; Wade, R; Patwardhan, A R; Kale, S

2012-01-01

Injuries related to the Hindu festival of Dahihandi where a human pyramid is formed and a pot of money kept at a height is broken, celebrated in the state of Maharashtra, have seen a significant rise in the past few years. The human pyramid formed is multi-layered and carries with it a high risk of injury including mortality. To evaluate the nature, extent and influencing factors of injuries related to Dahihandi festival. We present a retrospective analysis of patients who presented in a tertiary care center with injuries during the Dahihandi festival in the year 2010. 124 patients' records were evaluated for timing of injury, height of the Dahihandi pyramid, position of the patient in the multi-layered pyramid, mode of pyramid collapse and mechanism of an injury. A binary regression logistic analysis for risk factors was done at 5% significance level. Univariate and multi-variate binary logistic regression of the risk factors for occurrence of a major or minor injury was done using Minitab™ version 16.0 at 5% significance. Out of 139 patients presented to the center, 15 were not involved directly in the formation of pyramid, rest 124 were included in the analysis. A majority of the patients were above 15 years of age [110 (83.6%)]. 46 (37.1%) patients suffered major injuries. There were 39 fractures, 3 cases of chest wall trauma with 10 cases of head injuries and 1 death. More than half of the patients [78 (56.1%)] were injured after 1800 hours. 73 (58.9%) injured participants were part of the pyramid constructed to reach the Dahihandi placed at 30 feet or more above the ground. 72 (51.8%) participants were part of the middle layers of the pyramid. Fall of a participant from upstream layers on the body was the main mechanism of injury, and majority [101 (81.5%)] of the patients suffered injury during descent phase of the pyramid. There is a considerable risk of serious, life-threatening injuries inherent to human pyramid formation and descent in the Dahihandi festival. Safety guidelines are urgently needed to minimize risk and prevent loss of human life.

Earth Observations taken by the Expedition 17 Crew

NASA Image and Video Library

2008-05-30

ISS017-E-008285 (30 May 2008) --- Pyramids of Dashur, Egypt are featured in this image photographed by an Expedition 17 crewmember on the International Space Station. While the pyramids of Giza are perhaps the most famous, there are several other ancient Egyptian royal necropolis ("city of the dead") sites situated along the Nile River and its delta. One of these sites is located near the village of Dashur (upper right). The gray-brown built area of Dashur is surrounded by green agricultural land of the Nile Delta, which forms a distinct boundary with the tan desert to the west. It is in the desert that the monuments of the ancient rulers of Egypt are found. Several monuments are visible in this image, including the large Red and Bent Pyramids built by Snofru, first king of the 4th Dynasty that lasted from 2575-2465 BC. Other visible monuments include the pyramid complexes of Amenemhat III and Sesostris III, both kings of the 12th Dynasty (1991-1783 BC). Both of these complexes are poorly preserved, due both to unstable ground conditions, and dismantling of the limestone blocks forming the outer pyramid casings during later historical periods. The Bent Pyramid (lower right) is so called as the slope of the outer face was lessened halfway through construction, leading to a distinctive "bent" profile -- explanations for why this was done include decreasing the mass of the pyramid to prevent collapse, or to reduce the work necessary to complete it. The Red Pyramid to the north (center) was built after the Bent Pyramid, and is named for the coloration of the building stone at the structure's core. An irregular dark feature to the southeast of the Bent Pyramid is not a shadow cast by a monument; it is an irrigation feature extending into the desert.

Morphological characterization of rat entorhinal neurons in vivo: soma-dendritic structure and axonal domains.

PubMed

Lingenhöhl, K; Finch, D M

1991-01-01

We used in vivo intracellular labeling with horseradish peroxidase in order to study the soma-dendritic morphology and axonal projections of rat entorhinal neurons. The cells responded to hippocampal stimulation with inhibitory postsynaptic potentials, and thus likely received direct or indirect hippocampal input. All cells (n = 24) showed extensive dendritic domains that extended in some cases for more than 1 mm. The dendrites of layer II neurons were largely restricted to layers I and II or layers I-III, while the dendrites of deeper cells could extend through all cortical layers. Computed 3D rotations showed that the basilar dendrites of deep pyramids extended roughly parallel to the cortical layering, and that they were mostly confined to the layer containing the soma and layers immediately adjacent. Total dendritic lengths averaged 9.8 mm +/- 3.8 (SD), and ranged from 5 mm to more than 18 mm. Axonal processes could be visualized in 21 cells. Most of these showed axonal branching within the entorhinal cortex, sometimes extensive. Efferent axonal domains were reconstructed in detail in 3 layer II stellate cells. All 3 projected axons across the subicular complex to the dentate gyrus. One of these cells showed an extensive net-like axonal domain that also projected to several other structures, including the hippocampus proper, subicular complex, and the amygdalo-piriform transition area. The axons of layer III and IV cells projected to the angular bundle, where they continued in a rostral direction. In contrast to the layer II, III and IV cells, no efferent axonal branches leaving the entorhinal cortex could be visualized in 5 layer V neurons. The data indicate that entorhinal neurons can integrate input from a considerable volume of entorhinal cortex by virtue of their extensive dendritic domains, and provide a further basis for specifying the layers in which cells receive synaptic input. The extensive axonal branching pattern seen in most of the cells would support divergent propagation of their activity.

Micro-pyramidal structure fabrication on polydimethylsiloxane (PDMS) by Si (100) KOH wet etching

NASA Astrophysics Data System (ADS)

Hwang, Shinae; Lim, Kyungsuk; Shin, Hyeseon; Lee, Seongjae; Jang, Moongyu

2017-10-01

A high degree of accuracy in bulk micromachining is essential to fabricate micro-electro-mechanical systems (MEMS) devices. A series of etching experiments is carried out using 40 wt% KOH solutions at the constant temperature of 70 °C. Before wet etching, SF6 and O2 are used as the dry etching gas to etch the masking layers of a 100 nm thick Si3N4 and SiO2, respectively. The experimental results indicate that (100) silicon wafer form the pyramidal structures with (111) single crystal planes. All the etch profiles are analyzed using Scanning Electron Microscope (SEM) and the wet etch rates depend on the opening sizes. The manufactured pyramidal structures are used as the pattern of silicon mold. After a short hardening of coated polydimethylsiloxane (PDMS) layer, micro pyramidal structures are easily transferred to PDMS layer.

catena-Poly[bis(1,3-benzo­thia­zol-3-ium) [[di­chlorido­anti­monate(III)]-di-μ-chlorido-μ-oxido-[chlorido­anti­monate(III)]-μ-chlorido

PubMed Central

Chebout, Oussama; Boudraa, Mhamed; Bouacida, Sofiane; Merazig, Hocine; Boudaren, Chaouki

2016-01-01

The title compound, {(C7H6NS)2[Sb2Cl6O]}n, contains two benzo­thia­zolidium cations and one tri-μ-chlorido-tri­chlorido-μ-oxido-di­anti­monate(III) anion. The structure of the inorganic cation may be described as as being built up from two polyhedra, i.e. a square-pyramidal SbCl4O and a distorted octa­hedral SbOCl5 unit, sharing a common face (comprising the O atom and two Cl atoms). The two benzo­thia­zole cations are quasi-planar and subtend a dihedral angle of 19.93 (5)°. The crystal packing can be described by alternating (100) layers and [001] chains of the organic cations and inorganic anions connected through an extensive three-dimensional network of N—H⋯Cl, C—H⋯O and C—H⋯Cl hydrogen bonds. This is consolidated by slipped π–π stacking, with centroid-to-centroid distances between the benzo­thia­zole rings of 3.7111 (18)–3.8452 (16) Å. These inter­actions link the mol­ecules within the layers and also link the layers together and reinforce the cohesion of the ionic structure. PMID:26958390

Heterogeneity of spine density in pyramidal neurons of isocortex of mongoose, Herpestes edwardsii (É. Geoffroy Saint-Hilaire 1818).

PubMed

Srivastava, U C; Singh, Sippy; Chauhan, Prashant

2013-08-01

The characteristics of pyramidal neurons within six layers of Indian gray mongoose (Herpestes edwardsii) isocortex have been investigated using Golgi and Cresyl-Violet methods. Pyramidal neurons and the cytoarchitecture of isocortex of mongoose were photographed with the help of computer aided Nikon eclipse 80i microscope whereas the lucida drawings were made by simple light microscope equipped with camera lucida. The cortical neurons exhibit marked regional differences in phenotype. The differences occur in morphology and distribution of spines within the cortical neurons not only among different species but also within an animal's brain. The present investigation aims at studying the features of pyramidal neurons and to find out the differences if any in distribution of spines in different layers (II-VI) as well as regions (Frontal, Temporal, Parietal, and Occipital) of isocortex of mongoose, which will provide information regarding importance of different layer and region. This piece of work embarks the findings that spine density shows inter-regional as well as interlaminar variations within isocortex of mongoose indicating that pyramidal cells present in varied layer and region are not equally functional and there do exists differences in activity among layers and regions. Among regions, the Temporal region possessing highest spine density contributes more toward functioning of mongoose isocortex and might play significant role in predatory nature of mongoose because this region in mammals is associated with auditory, visual perception, and object recognition. Copyright © 2013 Wiley Periodicals, Inc.

Effect of 2,450 MHz microwave radiation on the development of the rat brain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inouye, M.; Galvin, M.J.; McRee, D.I.

1983-12-01

Male Sprague-Dawley rats were exposed to 2,450 MHz microwave radiation at an incident power density of 10 mW/cm2 daily for 3 hours from day 4 of pregnancy (in utero exposure) through day 40 postpartum, except for 2 days at the perinatal period. The animals were killed, and the brains removed, weighed, measured, and histologically examined at 15, 20, 30, and 40 days of age. The histologic parameters examined included the cortical architecture of the cerebral cortex, the decline of the germinal layer along the lateral ventricles, the myelination of the corpus callosum, and the decline of the external germinal layermore » of the cerebellar cortex. In 40-day-old rats, quantitative measurements of neurons were also made. The spine density of the pyramidal cells in layer III of the somatosensory cortex, and the density of basal dendritic trees of the pyramidal cells in layer V were measured in Golgi-Cox impregnated specimens. In addition, the density of Purkinje cells and the extent of the Purkinje cell layer in each lobule were measured in midsagittal sections of the cerebellum stained with thionin. There were no remarkable differences between microwave-exposed and control (sham-irradiated) groups for any of the histologic or quantitative parameters examined; however, the findings provide important information on quantitative measurements of the brain. The data from this study failed to demonstrate that there is a significant effect on rat brain development due to microwave exposure (10 mW/cm2) during the embryonic, fetal, and postnatal periods.« less

Distribution of CaMKIIα expression in the brain in vivo, studied by CaMKIIα-GFP mice

PubMed Central

Wang, Xinjun; Zhang, Chunzhao; Szábo, Gábor; Sun, Qian-Quan

2013-01-01

To facilitate the study of the CaMKIIα function in vivo, a CaMKIIα-GFP transgenic mouse line was generated. Here, our goal is to provide the first neuroanatomical characterization of GFP expression in the CNS of this line of mouse. Overall, CaMKIIα -GFP expression is strong and highly heterogeneous, with the dentate gyrus of the hippocampus as the most abundantly expressed region. In the hippocampus, around 70% of granule and pyramidal neurons expressed strong GFP. In the neocortex, presumed pyramidal neurons were GFP positive: around 32% of layer II/III and 35% of layer VI neurons expressed GFP, and a lower expression rate was found in other layers. In the thalamus and hypothalamus, strong GFP signals were detected in the neuropil. GFP-positive cells were also found in many other regions such as the spinal trigeminal nucleus, cerebellum and basal ganglia. We further compared the GFP expression with specific antibody staining for CaMKIIα and GABA. We found that GFP+ neurons were mostly positive for CaMKIIα-IR throughout the brain, with some exceptions throughout the brain, especially in the deeper layers of neocortex. GFP and GABA-IR marked distinct neuronal populations in most brain regions with the exception of granule cells in the olfactory bulb, purkinje cells in the cerebellar, and some layer I cells in neocortex. In conclusion, GFP expression in the CaMKIIα-GFP mice is similar to the endogenous expression of CaMKIIα protein, thus these mice can be used in in vivo and in vitro physiological studies in which visualization of CaMKIIα- neuronal populations is required. PMID:23632380

Pyramid Servings Database (PSDB) for NHANES III

Cancer.gov

The National Cancer Institute developed a database to examine dietary data from the National Center for Health Statistics' Third National Health and Nutrition Examination Survey in terms of servings from each of United States Department of Agriculture's The Food Guide Pyramid's major and minor food groups.

Roles of specific Kv channel types in repolarization of the action potential in genetically identified subclasses of pyramidal neurons in mouse neocortex

PubMed Central

Pathak, Dhruba; Guan, Dongxu

2016-01-01

The action potential (AP) is a fundamental feature of excitable cells that serves as the basis for long-distance signaling in the nervous system. There is considerable diversity in the appearance of APs and the underlying repolarization mechanisms in different neuronal types (reviewed in Bean BP. Nat Rev Neurosci 8: 451–465, 2007), including among pyramidal cell subtypes. In the present work, we used specific pharmacological blockers to test for contributions of Kv1, Kv2, or Kv4 channels to repolarization of single APs in two genetically defined subpopulations of pyramidal cells in layer 5 of mouse somatosensory cortex (etv1 and glt) as well as pyramidal cells from layer 2/3. These three subtypes differ in AP properties (Groh A, Meyer HS, Schmidt EF, Heintz N, Sakmann B, Krieger P. Cereb Cortex 20: 826–836, 2010; Guan D, Armstrong WE, Foehring RC. J Neurophysiol 113: 2014–2032, 2015) as well as laminar position, morphology, and projection targets. We asked what the roles of Kv1, Kv2, and Kv4 channels are in AP repolarization and whether the underlying mechanisms are pyramidal cell subtype dependent. We found that Kv4 channels are critically involved in repolarizing neocortical pyramidal cells. There are also pyramidal cell subtype-specific differences in the role for Kv1 channels. Only Kv4 channels were involved in repolarizing the narrow APs of glt cells. In contrast, in etv1 cells and layer 2/3 cells, the broader APs are partially repolarized by Kv1 channels in addition to Kv4 channels. Consistent with their activation in the subthreshold range, Kv1 channels also regulate AP voltage threshold in all pyramidal cell subtypes. PMID:26864770

Optimizing pyramided transgenic Bt crops for sustainable pest management.

PubMed

Carrière, Yves; Crickmore, Neil; Tabashnik, Bruce E

2015-02-01

Transgenic crop pyramids producing two or more Bacillus thuringiensis (Bt) toxins that kill the same insect pest have been widely used to delay evolution of pest resistance. To assess the potential of pyramids to achieve this goal, we analyze data from 38 studies that report effects of ten Bt toxins used in transgenic crops against 15 insect pests. We find that compared with optimal low levels of insect survival, survival on currently used pyramids is often higher for both susceptible insects and insects resistant to one of the toxins in the pyramid. Furthermore, we find that cross-resistance and antagonism between toxins used in pyramids are common, and that these problems are associated with the similarity of the amino acid sequences of domains II and III of the toxins, respectively. This analysis should assist in future pyramid design and the development of sustainable resistance management strategies.

GENE EXPRESSION CHANGES AFTER SEIZURE PRECONDITIONING IN THE THREE MAJOR HIPPOCAMPAL CELL LAYERS

PubMed Central

Borges, Karin; Shaw, Renee; Dingledine, Raymond

2008-01-01

Rodents experience hippocampal damage after status epilepticus (SE) mainly in pyramidal cells while sparing the dentate granule cell layer (DGCL). Hippocampal damage was prevented in rats that had been preconditioned by brief seizures on two consecutive days before SE. To identify neuroprotective genes and biochemical pathways changed after preconditioning we compared the effect of preconditioning on gene expression in the CA1 and CA3 pyramidal and DGCLs, harvested by laser capture microscopy. In the DGCL the expression of 632 genes was altered, compared to only 151 and 58 genes in CA1 and CA3 pyramidal cell layers. Most of the differentially expressed genes regulate tissue structure and intra- and extracellular signaling, including neurotransmission. A selective upregulation of energy metabolism transcripts occurred in CA1 pyramidal cells relative to the DGCL. These results reveal a broad transcriptional response of the DGCL to preconditioning, and suggest several mechanisms underlying the neuroprotective effect of preconditioning seizures. PMID:17239605

A Pyramid Scheme for Constructing Geologic Maps on Geobrowsers

NASA Astrophysics Data System (ADS)

Whitmeyer, S. J.; de Paor, D. G.; Daniels, J.; Jeremy, N.; Michael, R.; Santangelo, B.

2008-12-01

Hundreds of geologic maps have been draped onto Google Earth (GE) using the ground overlay tag of Keyhole Markup Language (KML) and dozens have been published on academic and survey web pages as downloadable KML or KMZ (zipped KML) files. The vast majority of these are small KML docs that link to single, large - often very large - image files (jpegs, tiffs, etc.) Files that exceed 50 MB in size defeat the purpose of GE as an interactive and responsive, and therefore fast, virtual terrain medium. KML supports super-overlays (a.k.a. image pyramids), which break large graphic files into manageable tiles that load only when they are in the visible region at a sufficient level of detail (LOD), and several automatic tile-generating applications have been written. The process of exporting map data from applications such as ArcGIS® to KML format is becoming more manageable but still poses challenges. Complications arise, for example, because of differences between grid-north at a point on a map and true north at the equivalent location on the virtual globe. In our recent field season, we devised ways of overcoming many of these obstacles in order to generate responsive, panable, zoomable geologic maps in which data is layered in a pyramid structure similar to the image pyramid used for default GE terrain. The structure of our KML code for each level of the pyramid is self-similar: (i) check whether the current tile is in the visible region, (ii) if so, render the current overlay, (iii) add the current data level, and (iv) using four network links, check the visibility and LOD of four nested tiles. By using this pyramid structure we provide the user with access to geologic and map data at multiple levels of observation. For example, when the viewpoint is distant, regional structures and stratigraphy (e.g. lithological groups and terrane boundaries) are visible. As the user zooms to lower elevations, formations and ultimately individual outcrops come into focus. The pyramid structure is ideally suited to geologic data which tends to be unevenly exposed across the earth's surface.

Cellular and laminar expression of Dab-1 during the postnatal critical period in cat visual cortex and the effects of dark rearing.

PubMed

Kiser, Paul J; Liu, Zijing; Wilt, Steven D; Mower, George D

2011-04-06

This study describes postnatal critical period changes in cellular and laminar expression of Dab-1, a gene shown to play a role in controlling neuronal positioning during embryonic brain development, in cat visual cortex and the effects of dark rearing (DR). At 1week, there is dense cellular staining which is uniform across cortical layers and very light neuropil staining. At the peak of the critical period (5weeks), dense cell staining is largely restricted to large pyramidal cells of deep layer III and layer V, there is faint cell body staining throughout all cortical layers, neuropil staining is markedly increased and uniform in layers III to VI. This dramatic change in laminar and cellular labeling is independent of visual input, since immunostaining is similar in 5-week DR cats. By 10weeks, the mature laminar and cellular staining pattern is established and the major subsequent change is a further reduction in the density of cellular staining in all cortical layers. Neuropil staining is pronounced and uniform across cortical layers. These developmental changes are altered by DR. Quantification by cell counts indicated that age and DR interact such that differences in cellular expression are opposite in direction between 5- and 20-week-old cats. This bidirectional regulation of cellular expression is the same in all cortical laminae. The bidirectional regulation of cellular expression matches the effects of age and DR on physiological plasticity during the critical period as assessed by ocular dominance shifts in response to monocular deprivation. Copyright © 2011 Elsevier B.V. All rights reserved.

Motor Training Promotes Both Synaptic and Intrinsic Plasticity of Layer II/III Pyramidal Neurons in the Primary Motor Cortex

PubMed Central

Kida, Hiroyuki; Tsuda, Yasumasa; Ito, Nana; Yamamoto, Yui; Owada, Yuji; Kamiya, Yoshinori; Mitsushima, Dai

2016-01-01

Motor skill training induces structural plasticity at dendritic spines in the primary motor cortex (M1). To further analyze both synaptic and intrinsic plasticity in the layer II/III area of M1, we subjected rats to a rotor rod test and then prepared acute brain slices. Motor skill consistently improved within 2 days of training. Voltage clamp analysis showed significantly higher α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/N-methyl-d-aspartate (AMPA/NMDA) ratios and miniature EPSC amplitudes in 1-day trained rats compared with untrained rats, suggesting increased postsynaptic AMPA receptors in the early phase of motor learning. Compared with untrained controls, 2-days trained rats showed significantly higher miniature EPSC amplitude and frequency. Paired-pulse analysis further demonstrated lower rates in 2-days trained rats, suggesting increased presynaptic glutamate release during the late phase of learning. One-day trained rats showed decreased miniature IPSC frequency and increased paired-pulse analysis of evoked IPSC, suggesting a transient decrease in presynaptic γ-aminobutyric acid (GABA) release. Moreover, current clamp analysis revealed lower resting membrane potential, higher spike threshold, and deeper afterhyperpolarization in 1-day trained rats—while 2-days trained rats showed higher membrane potential, suggesting dynamic changes in intrinsic properties. Our present results indicate dynamic changes in glutamatergic, GABAergic, and intrinsic plasticity in M1 layer II/III neurons after the motor training. PMID:27193420

Motor Training Promotes Both Synaptic and Intrinsic Plasticity of Layer II/III Pyramidal Neurons in the Primary Motor Cortex.

PubMed

Kida, Hiroyuki; Tsuda, Yasumasa; Ito, Nana; Yamamoto, Yui; Owada, Yuji; Kamiya, Yoshinori; Mitsushima, Dai

2016-08-01

Motor skill training induces structural plasticity at dendritic spines in the primary motor cortex (M1). To further analyze both synaptic and intrinsic plasticity in the layer II/III area of M1, we subjected rats to a rotor rod test and then prepared acute brain slices. Motor skill consistently improved within 2 days of training. Voltage clamp analysis showed significantly higher α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/N-methyl-d-aspartate (AMPA/NMDA) ratios and miniature EPSC amplitudes in 1-day trained rats compared with untrained rats, suggesting increased postsynaptic AMPA receptors in the early phase of motor learning. Compared with untrained controls, 2-days trained rats showed significantly higher miniature EPSC amplitude and frequency. Paired-pulse analysis further demonstrated lower rates in 2-days trained rats, suggesting increased presynaptic glutamate release during the late phase of learning. One-day trained rats showed decreased miniature IPSC frequency and increased paired-pulse analysis of evoked IPSC, suggesting a transient decrease in presynaptic γ-aminobutyric acid (GABA) release. Moreover, current clamp analysis revealed lower resting membrane potential, higher spike threshold, and deeper afterhyperpolarization in 1-day trained rats-while 2-days trained rats showed higher membrane potential, suggesting dynamic changes in intrinsic properties. Our present results indicate dynamic changes in glutamatergic, GABAergic, and intrinsic plasticity in M1 layer II/III neurons after the motor training. © The Author 2016. Published by Oxford University Press.

Layer-specific input to distinct cell types in layer 6 of monkey primary visual cortex.

PubMed

Briggs, F; Callaway, E M

2001-05-15

Layer 6 of monkey V1 contains a physiologically and anatomically diverse population of excitatory pyramidal neurons. Distinctive arborization patterns of axons and dendrites within the functionally specialized cortical layers define eight types of layer 6 pyramidal neurons and suggest unique information processing roles for each cell type. To address how input sources contribute to cellular function, we examined the laminar sources of functional excitatory input onto individual layer 6 pyramidal neurons using scanning laser photostimulation. We find that excitatory input sources correlate with cell type. Class I neurons with axonal arbors selectively targeting magnocellular (M) recipient layer 4Calpha receive input from M-dominated layer 4B, whereas class I neurons whose axonal arbors target parvocellular (P) recipient layer 4Cbeta receive input from P-dominated layer 2/3. Surprisingly, these neuronal types do not differ significantly in the inputs they receive directly from layers 4Calpha or 4Cbeta. Class II cells, which lack dense axonal arbors within layer 4C, receive excitatory input from layers targeted by their local axons. Specifically, type IIA cells project axons to and receive input from the deep but not superficial layers. Type IIB neurons project to and receive input from the deepest and most superficial, but not middle layers. Type IIC neurons arborize throughout the cortical layers and tend to receive inputs from all cortical layers. These observations have implications for the functional roles of different layer 6 cell types in visual information processing.

The immediate large-scale dendritic plasticity of cortical pyramidal neurons subjected to acute epidural compression.

PubMed

Chen, J-R; Wang, T-J; Wang, Y-J; Tseng, G-F

2010-05-05

Head trauma and acute disorders often instantly compress the cerebral cortex and lead to functional abnormalities. Here we used rat epidural bead implantation model and investigated the immediate changes following acute compression. The dendritic arbors of affected cortical pyramidal neurons were filled with intracellular dye and reconstructed 3-dimensionally for analysis. Compression was found to shorten the apical, but not basal, dendrites of underlying layer III and V cortical pyramidal neurons and reduced dendritic spines on the entire dendritic arbor immediately. Dendrogram analysis showed that in addition to distal, proximal apical dendrites also quickly reconfigured. We then focused on apical dendritic trunks and explored how proximal dendrites were rapidly altered. Compression instantly twisted the microtubules and deformed the membrane contour of dendritic trunks likely a result of the elastic nature of dendrites as immediate decompression restored it and stabilization of microtubules failed to block it. Subsequent adaptive remodeling restored plasmalemma and microtubules to normal appearance in 3 days likely via active mechanisms as taxol blocked the restoration of microtubules and in addition partly affected plasmalemmal reorganization which presumably engaged recycling of excess membrane. In short, the structural dynamics and the associated mechanisms that we revealed demonstrate how compression quickly altered the morphology of cortical output neurons and hence cortical functions consequently. (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Peripheral facial nerve lesions induce changes in the firing properties of primary motor cortex layer 5 pyramidal cells.

PubMed

Múnera, A; Cuestas, D M; Troncoso, J

2012-10-25

Facial nerve lesions elicit long-lasting changes in vibrissal primary motor cortex (M1) muscular representation in rodents. Reorganization of cortical representation has been attributed to potentiation of preexisting horizontal connections coming from neighboring muscle representation. However, changes in layer 5 pyramidal neuron activity induced by facial nerve lesion have not yet been explored. To do so, the effect of irreversible facial nerve injury on electrophysiological properties of layer 5 pyramidal neurons was characterized. Twenty-four adult male Wistar rats were randomly subjected to two experimental treatments: either surgical transection of mandibular and buccal branches of the facial nerve (n=18) or sham surgery (n=6). Unitary and population activity of vibrissal M1 layer 5 pyramidal neurons recorded in vivo under general anesthesia was compared between sham-operated and facial nerve-injured animals. Injured animals were allowed either one (n=6), three (n=6), or five (n=6) weeks recovery before recording in order to characterize the evolution of changes in electrophysiological activity. As compared to control, facial nerve-injured animals displayed the following sustained and significant changes in spontaneous activity: increased basal firing frequency, decreased spike-associated local field oscillation amplitude, and decreased spontaneous theta burst firing frequency. Significant changes in evoked-activity with whisker pad stimulation included: increased short latency population spike amplitude, decreased long latency population oscillations amplitude and frequency, and decreased peak frequency during evoked single-unit burst firing. Taken together, such changes demonstrate that peripheral facial nerve lesions induce robust and sustained changes of layer 5 pyramidal neurons in vibrissal motor cortex. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Region-specific spike frequency acceleration in Layer 5 pyramidal neurons mediated by Kv1 subunits

PubMed Central

Miller, Mark N; Okaty, Benjamin W; Nelson, Sacha B

2009-01-01

Separation of the cortical sheet into functionally distinct regions is a hallmark of neocortical organization. Cortical circuit function emerges from afferent and efferent connectivity, local connectivity within the cortical microcircuit, and the intrinsic membrane properties of neurons that comprise the circuit. While localization of functions to particular cortical areas can be partially accounted for by regional differences in both long range and local connectivity, it is unknown whether the intrinsic membrane properties of cortical cell-types differ between cortical regions. Here we report the first example of a region-specific firing type in layer 5 pyramidal neurons, and show that the intrinsic membrane and integrative properties of a discrete subtype of layer 5 pyramidal neurons differ between primary motor and somatosensory cortices due to region and cell-type-specific Kv1 subunit expression. PMID:19091962

The structure directing effect of organic cations onto the crystal structures of layered thioantimonates(III): Solvothermal synthesis and crystal structures of five new compounds containing the 2∞[Sb 8S 13] 2- anion

NASA Astrophysics Data System (ADS)

Puls, Angela; Näther, Christian; Kiebach, Ragnar; Bensch, Wolfgang

2006-09-01

The five new thioantimonates(III) ( iprH) 2[Sb 8S 13] ( I), (1,2-dapH) 2[Sb 8S 13] ( II), (1,3-dapH 2)[Sb 8S 13] ( III), (dienH 2)[Sb 8S 13]ṡ1.5H 2O ( IV), and (C 6H 9N 2)[Sb 8S 13]ṡ2.5H 2O ( V) were synthesised under solvothermal conditions ( ipr = iso-propylamine; 1,2-dap = 1,2-diaminopropane; 1,3-dap = 1,3-diaminopropane; dien = diethylentriamine; C 6H 9N 2 = 3-(aminoethyl)-pyridine). The structures of compounds I and II are topological very similar and a central motif is a Sb 10S 10 ring. On both sides of this ring Sb 5S 5 rings are condensed. These rings are connected via Sb 4S 4 rings leading to the sequence Sb 10S 10-Sb 5S 5-Sb 4S 4-Sb 5S 5-Sb 10Sb 10 in the [010] direction. Further interconnection into the two-dimensional [Sb 8S 13] 2- anion produces a large central Sb 18S 18 ring with dimensions of 11ṡ11 Å in both compounds. The two atoms thick layers are linear and stacked along the a axis generating large channels running along [010]. The layered anion of compound III is constructed by interconnection of the SbS 3 and SbS 4 units yielding Sb 19S 19, Sb 14S 14, Sb 13S 13, and Sb 8S 8 rings. The linear layers are two atoms thick and are stacked perpendicular to [001] to form channels running along the same direction. The last two compounds IV and V show a similar network topology. The layered anion is constructed by SbS 3 trigonal pyramids and SbS 4 units. The layer contains a Sb 12S 12 rings as the main structural motif. The corrugated layers extending in the (100) plane are two atoms thick and are stacked in a manner that large tunnels run along [100]. The total potential solvent areas are large and range from 20.7% for III to 35% for II.

Age-Based Comparison of Human Dendritic Spine Structure Using Complete Three-Dimensional Reconstructions

PubMed Central

Benavides-Piccione, Ruth; Fernaud-Espinosa, Isabel; Robles, Victor; Yuste, Rafael; DeFelipe, Javier

2013-01-01

Dendritic spines of pyramidal neurons are targets of most excitatory synapses in the cerebral cortex. Recent evidence suggests that the morphology of the dendritic spine could determine its synaptic strength and learning rules. However, unfortunately, there are scant data available regarding the detailed morphology of these structures for the human cerebral cortex. In the present study, we analyzed over 8900 individual dendritic spines that were completely 3D reconstructed along the length of apical and basal dendrites of layer III pyramidal neurons in the cingulate cortex of 2 male humans (aged 40 and 85 years old), using intracellular injections of Lucifer Yellow in fixed tissue. We assembled a large, quantitative database, which revealed a major reduction in spine densities in the aged case. Specifically, small and short spines of basal dendrites and long spines of apical dendrites were lost, regardless of the distance from the soma. Given the age difference between the cases, our results suggest selective alterations in spines with aging in humans and indicate that the spine volume and length are regulated by different biological mechanisms. PMID:22710613

Vertically integrated (Ga, In)N nanostructures for future single photon emitters operating in the telecommunication wavelength range

NASA Astrophysics Data System (ADS)

Winden, A.; Mikulics, M.; Grützmacher, D.; Hardtdegen, H.

2013-10-01

Important technological steps are discussed and realized for future room-temperature operation of III-nitride single photon emitters. First, the growth technology of positioned single pyramidal InN nanostructures capped by Mg-doped GaN is presented. The optimization of their optical characteristics towards narrowband emission in the telecommunication wavelength range is demonstrated. In addition, a device concept and technology was developed so that the nanostructures became singularly addressable. It was found that the nanopyramids emit in the telecommunication wavelength range if their size is chosen appropriately. A p-GaN contacting layer was successfully produced as a cap to the InN pyramids and the top p-contact was achievable using an intrinsically conductive polymer PEDOT:PSS, allowing a 25% increase in light transmittance compared to standard Ni/Au contact technology. Single nanopyramids were successfully integrated into a high-frequency device layout. These decisive technology steps provide a promising route to electrically driven and room-temperature operating InN based single photon emitters in the telecommunication wavelength range.

d-LSD-induced c-Fos expression occurs in a population of oligodendrocytes in rat prefrontal cortex.

PubMed

Reissig, Chad J; Rabin, Richard A; Winter, Jerrold C; Dlugos, Cynthia A

2008-03-31

Induction of mRNA or protein for immediate-early genes, such as c-fos, is used to identify brain areas, specific cell types, and neuronal circuits that become activated in response to various stimuli including psychoactive drugs. The objective of the present study was to identify the cell types in the prefrontal cortex in which lysergic acid diethylamide (d-LSD) induces c-Fos expression. Systemic administration of d-LSD resulted in a dose-dependent increase in c-Fos immunoreactivity. Although c-Fos-positive cells were found in all cortical layers, they were most numerous in layers III, IV, and V. d-LSD-induced c-Fos immunoreactivity was found in cells co-labeled with anti-neuron-specific enolase or anti-oligodendrocyte Oligo1. The Oligo1-labeled cells had small, round bodies and nuclear diameters characteristic of oligodendrocytes. Studies using confocal microscopy confirmed colocalization of c-Fos-labeled nuclei in NeuN-labeled neurons. Astrocytes and microglia labeled with glial fibrillary acidic protein antibody and OX-42 antibody, respectively, did not display LSD-induced c-Fos expression. Pyramidal neurons labeled with anti-neurofilament antibody also did not show induction of c-Fos immunoreactivity after systemic d-LSD administration. The present study demonstrates that d-LSD induced expression of c-Fos in the prefrontal cortex occurs in subpopulations of neurons and in oligodendrocytes, but not in pyramidal neurons, astrocytes, and microglia.

Effect of Anatomically Realistic Full-Head Model on Activation of Cortical Neurons in Subdural Cortical Stimulation—A Computational Study

NASA Astrophysics Data System (ADS)

Seo, Hyeon; Kim, Donghyeon; Jun, Sung Chan

2016-06-01

Electrical brain stimulation (EBS) is an emerging therapy for the treatment of neurological disorders, and computational modeling studies of EBS have been used to determine the optimal parameters for highly cost-effective electrotherapy. Recent notable growth in computing capability has enabled researchers to consider an anatomically realistic head model that represents the full head and complex geometry of the brain rather than the previous simplified partial head model (extruded slab) that represents only the precentral gyrus. In this work, subdural cortical stimulation (SuCS) was found to offer a better understanding of the differential activation of cortical neurons in the anatomically realistic full-head model than in the simplified partial-head models. We observed that layer 3 pyramidal neurons had comparable stimulation thresholds in both head models, while layer 5 pyramidal neurons showed a notable discrepancy between the models; in particular, layer 5 pyramidal neurons demonstrated asymmetry in the thresholds and action potential initiation sites in the anatomically realistic full-head model. Overall, the anatomically realistic full-head model may offer a better understanding of layer 5 pyramidal neuronal responses. Accordingly, the effects of using the realistic full-head model in SuCS are compelling in computational modeling studies, even though this modeling requires substantially more effort.

Serotonergic Suppression of Mouse Prefrontal Circuits Implicated in Task Attention

PubMed Central

2016-01-01

Serotonin (5-HT) regulates attention by neurobiological mechanisms that are not well understood. Layer 6 (L6) pyramidal neurons of prefrontal cortex play an important role in attention and express 5-HT receptors, but the serotonergic modulation of this layer and its excitatory output is not known. Here, we performed whole-cell recordings and pharmacological manipulations in acute brain slices from wild-type and transgenic mice expressing either eGFP or eGFP-channelrhodopsin in prefrontal L6 pyramidal neurons. Excitatory circuits between L6 pyramidal neurons and L5 GABAergic interneurons, including a population of interneurons essential for task attention, were investigated using optogenetic techniques. Our experiments show that prefrontal L6 pyramidal neurons are subject to strong serotonergic inhibition and demonstrate direct 5-HT–sensitive connections between prefrontal L6 pyramidal neurons and two classes of L5 interneurons. This work helps to build a neurobiological framework to appreciate serotonergic disruption of task attention and yields insight into the disruptions of attention observed in psychiatric disorders with altered 5-HT receptors and signaling. PMID:27844060

Synthesis, structure and characterization of two new copper(I)-thioarsenates (III) constructed by the [AsS{sub 3}]{sup 3-} and CuS{sub x} units

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Hua-Gang; Ji, Min; Ji, Shou-Hua

2013-02-15

Two new copper(I)-thioarsenates(III), CsCu{sub 2}AsS{sub 3}(1) and KCu{sub 4}AsS{sub 4}(2), have been synthesized solvothermally in the presence of copper powder. Compound 1 is built up of trigonal AsS{sub 3} pyramid, tetrahedral CuAsS{sub 3} and CuS{sub 3} moieties forming 4-membered, 5-membered and 6-membered rings. The fusion of these rings produces layered anions [Cu{sub 2}AsS{sub 3}]{sup -}, and cesium cations are located between metal-sulfide layers. The structure of 2 consists of infinite [Cu{sub 2}S{sub 2}]{sup 2-} chain and layered [Cu{sub 6}As{sub 2}S{sub 6}] linked to form a three-dimensional anionic framework, [Cu{sub 4}AsS{sub 4}]{sup -}, and containing channels in which the potassium cationsmore » reside. - Graphical abstract: Qne layered CsCu{sub 2}AsS{sub 3} and one framework KCu{sub 4}AsS{sub 4} possessing noncondensed [AsS{sub 3}]{sup 3-} unit have been synthesized solvothermally. The optical band gaps of the two compounds are 2.3 and 1.8 eV, respectively. Highlights: Black-Right-Pointing-Pointer We obtained two new copper(I)-thioarsenate(III), CsCu{sub 2}AsS{sub 3} and KCu{sub 4}AsS{sub 4}. Black-Right-Pointing-Pointer Both compounds possess noncondensed [AsS{sub 3}]{sup 3-} unit and represent new structure types. Black-Right-Pointing-Pointer The optical band gaps of the two compounds are 2.3 eV and 1.8 eV, respectively.« less

Urban Public Health: Is There a Pyramid?

PubMed Central

Su, Meirong; Chen, Bin; Yang, Zhifeng; Cai, Yanpeng; Wang, Jiao

2013-01-01

Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH). Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London) are compared from the point of view of five aspects, namely physical health, living conditions, social security, environmental quality, and education and culture. A pyramid structure was found in each city when focusing on 2000–2009 data. The pyramid of Beijing is relatively similar to that of Tokyo, and the pyramids of New York and London are similar to each other. A general development trend in UPH is proposed and represented by different pyramid modes. As a basic conjecture, the UPH pyramid model can be verified and developed with data of more cities over a longer period, and be used to promote healthy urban development. PMID:23358233

Urban public health: is there a pyramid?

PubMed

Su, Meirong; Chen, Bin; Yang, Zhifeng; Cai, Yanpeng; Wang, Jiao

2013-01-28

Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH). Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London) are compared from the point of view of five aspects, namely physical health, living conditions, social security, environmental quality, and education and culture. A pyramid structure was found in each city when focusing on 2000-2009 data. The pyramid of Beijing is relatively similar to that of Tokyo, and the pyramids of New York and London are similar to each other. A general development trend in UPH is proposed and represented by different pyramid modes. As a basic conjecture, the UPH pyramid model can be verified and developed with data of more cities over a longer period, and be used to promote healthy urban development.

Revealing Surface Waters on an Antifreeze Protein by Fusion Protein Crystallography Combined with Molecular Dynamic Simulations.

PubMed

Sun, Tianjun; Gauthier, Sherry Y; Campbell, Robert L; Davies, Peter L

2015-10-08

Antifreeze proteins (AFPs) adsorb to ice through an extensive, flat, relatively hydrophobic surface. It has been suggested that this ice-binding site (IBS) organizes surface waters into an ice-like clathrate arrangement that matches and fuses to the quasi-liquid layer on the ice surface. On cooling, these waters join the ice lattice and freeze the AFP to its ligand. Evidence for the generality of this binding mechanism is limited because AFPs tend to crystallize with their IBS as a preferred protein-protein contact surface, which displaces some bound waters. Type III AFP is a 7 kDa globular protein with an IBS made up two adjacent surfaces. In the crystal structure of the most active isoform (QAE1), the part of the IBS that docks to the primary prism plane of ice is partially exposed to solvent and has clathrate waters present that match this plane of ice. The adjacent IBS, which matches the pyramidal plane of ice, is involved in protein-protein crystal contacts with few surface waters. Here we have changed the protein-protein contacts in the ice-binding region by crystallizing a fusion of QAE1 to maltose-binding protein. In this 1.9 Å structure, the IBS that fits the pyramidal plane of ice is exposed to solvent. By combining crystallography data with MD simulations, the surface waters on both sides of the IBS were revealed and match well with the target ice planes. The waters on the pyramidal plane IBS were loosely constrained, which might explain why other isoforms of type III AFP that lack the prism plane IBS are less active than QAE1. The AFP fusion crystallization method can potentially be used to force the exposure to solvent of the IBS on other AFPs to reveal the locations of key surface waters.

Conserved size and periodicity of pyramidal patches in layer 2 of medial/caudal entorhinal cortex

PubMed Central

Naumann, Robert K.; Ray, Saikat; Prokop, Stefan; Las, Liora; Heppner, Frank L.

2016-01-01

ABSTRACT To understand the structural basis of grid cell activity, we compare medial entorhinal cortex architecture in layer 2 across five mammalian species (Etruscan shrews, mice, rats, Egyptian fruit bats, and humans), bridging ∼100 million years of evolutionary diversity. Principal neurons in layer 2 are divided into two distinct cell types, pyramidal and stellate, based on morphology, immunoreactivity, and functional properties. We confirm the existence of patches of calbindin‐positive pyramidal cells across these species, arranged periodically according to analyses techniques like spatial autocorrelation, grid scores, and modifiable areal unit analysis. In rodents, which show sustained theta oscillations in entorhinal cortex, cholinergic innervation targeted calbindin patches. In bats and humans, which only show intermittent entorhinal theta activity, cholinergic innervation avoided calbindin patches. The organization of calbindin‐negative and calbindin‐positive cells showed marked differences in entorhinal subregions of the human brain. Layer 2 of the rodent medial and the human caudal entorhinal cortex were structurally similar in that in both species patches of calbindin‐positive pyramidal cells were superimposed on scattered stellate cells. The number of calbindin‐positive neurons in a patch increased from ∼80 in Etruscan shrews to ∼800 in humans, only an ∼10‐fold over a 20,000‐fold difference in brain size. The relatively constant size of calbindin patches differs from cortical modules such as barrels, which scale with brain size. Thus, selective pressure appears to conserve the distribution of stellate and pyramidal cells, periodic arrangement of calbindin patches, and relatively constant neuron number in calbindin patches in medial/caudal entorhinal cortex. J. Comp. Neurol. 524:783–806, 2016. © 2015 The Authors. The Journal of Comparative Neurology Published by Wiley Periodicals, Inc. PMID:26223342

Conserved size and periodicity of pyramidal patches in layer 2 of medial/caudal entorhinal cortex.

PubMed

Naumann, Robert K; Ray, Saikat; Prokop, Stefan; Las, Liora; Heppner, Frank L; Brecht, Michael

2016-03-01

To understand the structural basis of grid cell activity, we compare medial entorhinal cortex architecture in layer 2 across five mammalian species (Etruscan shrews, mice, rats, Egyptian fruit bats, and humans), bridging ∼100 million years of evolutionary diversity. Principal neurons in layer 2 are divided into two distinct cell types, pyramidal and stellate, based on morphology, immunoreactivity, and functional properties. We confirm the existence of patches of calbindin-positive pyramidal cells across these species, arranged periodically according to analyses techniques like spatial autocorrelation, grid scores, and modifiable areal unit analysis. In rodents, which show sustained theta oscillations in entorhinal cortex, cholinergic innervation targeted calbindin patches. In bats and humans, which only show intermittent entorhinal theta activity, cholinergic innervation avoided calbindin patches. The organization of calbindin-negative and calbindin-positive cells showed marked differences in entorhinal subregions of the human brain. Layer 2 of the rodent medial and the human caudal entorhinal cortex were structurally similar in that in both species patches of calbindin-positive pyramidal cells were superimposed on scattered stellate cells. The number of calbindin-positive neurons in a patch increased from ∼80 in Etruscan shrews to ∼800 in humans, only an ∼10-fold over a 20,000-fold difference in brain size. The relatively constant size of calbindin patches differs from cortical modules such as barrels, which scale with brain size. Thus, selective pressure appears to conserve the distribution of stellate and pyramidal cells, periodic arrangement of calbindin patches, and relatively constant neuron number in calbindin patches in medial/caudal entorhinal cortex. © 2015 The Authors. The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

Canonical Organization of Layer 1 Neuron-Led Cortical Inhibitory and Disinhibitory Interneuronal Circuits

PubMed Central

Lee, Alice J.; Wang, Guangfu; Jiang, Xiaolong; Johnson, Seraphina M.; Hoang, Elizabeth T.; Lanté, Fabien; Stornetta, Ruth L.; Beenhakker, Mark P.; Shen, Ying; Julius Zhu, J.

2015-01-01

Interneurons play a key role in cortical function and dysfunction, yet organization of cortical interneuronal circuitry remains poorly understood. Cortical Layer 1 (L1) contains 2 general GABAergic interneuron groups, namely single bouquet cells (SBCs) and elongated neurogliaform cells (ENGCs). SBCs predominantly make unidirectional inhibitory connections (SBC→) with L2/3 interneurons, whereas ENGCs frequently form reciprocal inhibitory and electric connections (ENGC↔) with L2/3 interneurons. Here, we describe a systematic investigation of the pyramidal neuron targets of L1 neuron-led interneuronal circuits in the rat barrel cortex with simultaneous octuple whole-cell recordings and report a simple organizational scheme of the interneuronal circuits. Both SBCs→ and ENGC ↔ L2/3 interneuronal circuits connect to L2/3 and L5, but not L6, pyramidal neurons. SBC → L2/3 interneuronal circuits primarily inhibit the entire dendritic–somato–axonal axis of a few L2/3 and L5 pyramidal neurons located within the same column. In contrast, ENGC ↔ L2/3 interneuronal circuits generally inhibit the distal apical dendrite of many L2/3 and L5 pyramidal neurons across multiple columns. Finally, L1 interneuron-led circuits target distinct subcellular compartments of L2/3 and L5 pyramidal neurons in a L2/3 interneuron type-dependent manner. These results suggest that L1 neurons form canonical interneuronal circuits to control information processes in both supra- and infragranular cortical layers. PMID:24554728

Pyramidal dislocation induced strain relaxation in hexagonal structured InGaN/AlGaN/GaN multilayer

NASA Astrophysics Data System (ADS)

Yan, P. F.; Du, K.; Sui, M. L.

2012-10-01

Due to the special dislocation slip systems in hexagonal lattice, dislocation dominated deformations in hexagonal structured multilayers are significantly different from that in cubic structured systems. In this work, we have studied the strain relaxation mechanism in hexagonal structured InGaN/AlGaN/GaN multilayers with transmission electron microscopy. Due to lattice mismatch, the strain relaxation was found initiated with the formation of pyramidal dislocations. Such dislocations locally lie at only one preferential slip direction in the hexagonal lattice. This preferential slip causes a shear stress along the basal planes and consequently leads to dissociation of pyramidal dislocations and operation of the basal plane slip system. The compressive InGaN layers and "weak" AlGaN/InGaN interfaces stimulate the dissociation of pyramidal dislocations at the interfaces. These results enhance the understanding of interactions between dislocations and layer interfaces and shed new lights on deformation mechanism in hexagonal-lattice multilayers.

Asymmetric temporal integration of layer 4 and layer 2/3 inputs in visual cortex.

PubMed

Hang, Giao B; Dan, Yang

2011-01-01

Neocortical neurons in vivo receive concurrent synaptic inputs from multiple sources, including feedforward, horizontal, and feedback pathways. Layer 2/3 of the visual cortex receives feedforward input from layer 4 and horizontal input from layer 2/3. Firing of the pyramidal neurons, which carries the output to higher cortical areas, depends critically on the interaction of these pathways. Here we examined synaptic integration of inputs from layer 4 and layer 2/3 in rat visual cortical slices. We found that the integration is sublinear and temporally asymmetric, with larger responses if layer 2/3 input preceded layer 4 input. The sublinearity depended on inhibition, and the asymmetry was largely attributable to the difference between the two inhibitory inputs. Interestingly, the asymmetric integration was specific to pyramidal neurons, and it strongly affected their spiking output. Thus via cortical inhibition, the temporal order of activation of layer 2/3 and layer 4 pathways can exert powerful control of cortical output during visual processing.

Lanthanide-Connecting and Lone-Electron-Pair Active Trigonal-Pyramidal-AsO3 Inducing Nanosized Poly(polyoxotungstate) Aggregates and Their Anticancer Activities

NASA Astrophysics Data System (ADS)

Zhao, Jun-Wei; Li, Hai-Lou; Ma, Xing; Xie, Zhigang; Chen, Li-Juan; Zhu, Yongsheng

2016-05-01

By virtue of the stereochemical effect of the lone-electron pair located on the trigonal-pyramidal-AsO3 groups and the one-pot self-assembly strategy in the conventional aqueous solution, a series of novel lanthanide-bridging and lone-electron-pair active trigonal-pyramidal-AsO3 inducing nanosized poly(polyoxotungstate) aggregates [H2N(CH3)2]6 Na24H16{[Ln10W16(H2O)30O50](B-α-AsW9O33)8}·97H2O [Ln = EuIII (1), SmIII (2), GdIII (3), TbIII (4), DyIII (5), HoIII (6), ErIII (7), TmIII (8)] were prepared and further characterized by elemental analyses, IR spectra, UV spectra, thermogravimetric (TG) analyses and single-crystal X-ray diffraction. The most remarkable structural feature is that the polyanionic skeleton of {[Ln10W16(H2O)30O50](B-α-AsW9O33)8}46- is constructed from eight trivacant Keggin [B-α-AsW9O33]9- fragments through ten Ln centers and sixteen bridging W atoms in the participation of fifty extraneous oxygen atoms. Notably, 4 and 8 can be stable in the aqueous solution not only for eight days but also in the range of pH = 3.9-7.5. Moreover, the cytotoxicity tests of 4 and 8 toward human cervical cancer (HeLa) cells, human breast cancer (MCF-7) cells and mouse fibroblast (L929) cells were performed by the 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and the cell apoptosis processes were characterized by calcein AM/PI staining experiments, annexin V-FITC/PI staining experiments and morphological changes.

Kinetic Model of the Initial Stage of the Nanowire Growth

NASA Astrophysics Data System (ADS)

Filimonov, S. N.; Hervieu, Yu. Yu.

2018-03-01

A kinetic model of the formation of pyramid-like bulges (pedestals) at the bases of vertical nanowires is proposed. The formation of the pedestals at the early stage of the nanowire growth is assumed to be induced by a higher nucleation rate of two-dimensional islands under the catalyst droplet, as compared to the nucleation rate at the non-activated surface areas. Kinetics of the nucleation and propagation of the steps in the pyramid is described with a model of the multilayer growth, taking into account that the catalyst droplet at the nanowire top is a strong sink for adatoms. It is shown that the transition from the growth of the pyramid to the axial growth of the nanowire is possible if the appearance of a nucleus of the new layer under the catalyst droplet results in a partial dissolution of the underlying layer. In this case a segment of the nanowire sidewall is formed, preventing the lateral growth of the layers generated by the droplet.

Differences in the Electrophysiological Properties of Mouse Somatosensory Layer 2/3 Neurons In Vivo and Slice Stem from Intrinsic Sources Rather than a Network-Generated High Conductance State

PubMed Central

2018-01-01

Abstract Synaptic activity in vivo can potentially alter the integration properties of neurons. Using recordings in awake mice, we targeted somatosensory layer 2/3 pyramidal neurons and compared neuronal properties with those from slices. Pyramidal cells in vivo had lower resistance and gain values, as well as broader spikes and increased spike frequency adaptation compared to the same cells in slices. Increasing conductance in neurons using dynamic clamp to levels observed in vivo, however, did not lessen the differences between in vivo and slice conditions. Further, local application of tetrodotoxin (TTX) in vivo blocked synaptic-mediated membrane voltage fluctuations but had little impact on pyramidal cell membrane input resistance and time constant values. Differences in electrophysiological properties of layer 2/3 neurons in mouse somatosensory cortex, therefore, stem from intrinsic sources separate from synaptic-mediated membrane voltage fluctuations. PMID:29662946

Back-Propagation of Physiological Action Potential Output in Dendrites of Slender-Tufted L5A Pyramidal Neurons

PubMed Central

Grewe, Benjamin F.; Bonnan, Audrey; Frick, Andreas

2009-01-01

Pyramidal neurons of layer 5A are a major neocortical output type and clearly distinguished from layer 5B pyramidal neurons with respect to morphology, in vivo firing patterns, and connectivity; yet knowledge of their dendritic properties is scant. We used a combination of whole-cell recordings and Ca2+ imaging techniques in vitro to explore the specific dendritic signaling role of physiological action potential patterns recorded in vivo in layer 5A pyramidal neurons of the whisker-related ‘barrel cortex’. Our data provide evidence that the temporal structure of physiological action potential patterns is crucial for an effective invasion of the main apical dendrites up to the major branch point. Both the critical frequency enabling action potential trains to invade efficiently and the dendritic calcium profile changed during postnatal development. In contrast to the main apical dendrite, the more passive properties of the short basal and apical tuft dendrites prevented an efficient back-propagation. Various Ca2+ channel types contributed to the enhanced calcium signals during high-frequency firing activity, whereas A-type K+ and BKCa channels strongly suppressed it. Our data support models in which the interaction of synaptic input with action potential output is a function of the timing, rate and pattern of action potentials, and dendritic location. PMID:20508744

Tris(O-cyclo-hexyl dithio-carbonato-κS)anti-mony(III).

PubMed

Li, Wenkuan; Yin, Handong; Wen, Liyuan; Wang, Daqi

2008-12-10

In the mol-ecule of the title compound, [Sb(C(7)H(11)OS(2))(3)], the anti-mony(III) is coordinated by the S atoms of three O-alkyl xanthate groups acting as monodentate ligands, forming a distorted trigonal-pyramidal coordination.

Regulation of the Hippocampal Network by VGLUT3-Positive CCK- GABAergic Basket Cells

PubMed Central

Fasano, Caroline; Rocchetti, Jill; Pietrajtis, Katarzyna; Zander, Johannes-Friedrich; Manseau, Frédéric; Sakae, Diana Y.; Marcus-Sells, Maya; Ramet, Lauriane; Morel, Lydie J.; Carrel, Damien; Dumas, Sylvie; Bolte, Susanne; Bernard, Véronique; Vigneault, Erika; Goutagny, Romain; Ahnert-Hilger, Gudrun; Giros, Bruno; Daumas, Stéphanie; Williams, Sylvain; El Mestikawy, Salah

2017-01-01

Hippocampal interneurons release the inhibitory transmitter GABA to regulate excitation, rhythm generation and synaptic plasticity. A subpopulation of GABAergic basket cells co-expresses the GABA/glycine vesicular transporters (VIAAT) and the atypical type III vesicular glutamate transporter (VGLUT3); therefore, these cells have the ability to signal with both GABA and glutamate. GABAergic transmission by basket cells has been extensively characterized but nothing is known about the functional implications of VGLUT3-dependent glutamate released by these cells. Here, using VGLUT3-null mice we observed that the loss of VGLUT3 results in a metaplastic shift in synaptic plasticity at Shaeffer’s collaterals – CA1 synapses and an altered theta oscillation. These changes were paralleled by the loss of a VGLUT3-dependent inhibition of GABAergic current in CA1 pyramidal layer. Therefore presynaptic type III metabotropic could be activated by glutamate released from VGLUT3-positive interneurons. This putative presynaptic heterologous feedback mechanism inhibits local GABAergic tone and regulates the hippocampal neuronal network. PMID:28559797

Distribution and Function of HCN Channels in the Apical Dendritic Tuft of Neocortical Pyramidal Neurons

PubMed Central

Harnett, Mark T.; Magee, Jeffrey C.

2015-01-01

The apical tuft is the most remote area of the dendritic tree of neocortical pyramidal neurons. Despite its distal location, the apical dendritic tuft of layer 5 pyramidal neurons receives substantial excitatory synaptic drive and actively processes corticocortical input during behavior. The properties of the voltage-activated ion channels that regulate synaptic integration in tuft dendrites have, however, not been thoroughly investigated. Here, we use electrophysiological and optical approaches to examine the subcellular distribution and function of hyperpolarization-activated cyclic nucleotide-gated nonselective cation (HCN) channels in rat layer 5B pyramidal neurons. Outside-out patch recordings demonstrated that the amplitude and properties of ensemble HCN channel activity were uniform in patches excised from distal apical dendritic trunk and tuft sites. Simultaneous apical dendritic tuft and trunk whole-cell current-clamp recordings revealed that the pharmacological blockade of HCN channels decreased voltage compartmentalization and enhanced the generation and spread of apical dendritic tuft and trunk regenerative activity. Furthermore, multisite two-photon glutamate uncaging demonstrated that HCN channels control the amplitude and duration of synaptically evoked regenerative activity in the distal apical dendritic tuft. In contrast, at proximal apical dendritic trunk and somatic recording sites, the blockade of HCN channels decreased excitability. Dynamic-clamp experiments revealed that these compartment-specific actions of HCN channels were heavily influenced by the local and distributed impact of the high density of HCN channels in the distal apical dendritic arbor. The properties and subcellular distribution pattern of HCN channels are therefore tuned to regulate the interaction between integration compartments in layer 5B pyramidal neurons. PMID:25609619

Sub- and suprathreshold receptive field properties of pyramidal neurones in layers 5A and 5B of rat somatosensory barrel cortex

PubMed Central

Manns, Ian D; Sakmann, Bert; Brecht, Michael

2004-01-01

Layer 5 (L5) pyramidal neurones constitute a major sub- and intracortical output of the somatosensory cortex. This layer 5 is segregated into layers 5A and 5B which receive and distribute relatively independent afferent and efferent pathways. We performed in vivo whole-cell recordings from L5 neurones of the somatosensory (barrel) cortex of urethane-anaesthetized rats (aged 27–31 days). By delivering 6 deg single whisker deflections, whisker pad receptive fields were mapped for 16 L5A and 11 L5B neurones located below the layer 4 whisker-barrels. Average resting membrane potentials were −75.6±1.1 mV, and spontaneous action potential (AP) rates were 0.54± 0.14 APs s−1. Principal whisker (PW) evoked responses were similar in L5A and L5B neurones, with an average 5.0 ± 0.6 mV postsynaptic potential (PSP) and 0.12 ± 0.03 APs per stimulus. The layer 5A sub- and suprathreshold receptive fields (RFs) were more confined to the principle whisker than those of layer 5B. The basal dendritic arbors of layer 5A and 5B cells were located below both layer 4 barrels and septa, and the cell bodies were biased towards the barrel walls. Responses in both L5A and L5B developed slowly, with onset latencies of 10.1 ± 0.5 ms and peak latencies of 33.9 ± 3.3 ms. Contralateral multi-whisker stimulation evoked PSPs similar in amplitude to those of PW deflections; whereas, ipsilateral stimulation evoked smaller and longer latency PSPs. We conclude that in L5 a whisker deflection is represented in two ways: focally by L5A pyramids and more diffusely by L5B pyramids as a result of combining different inputs from lemniscal and paralemniscal pathways. The relevant output evoked by a whisker deflection could be the ensemble activity in the anatomically defined cortical modules associated with a single or a few barrel-columns. PMID:14724202

Encoding of Spatio-Temporal Input Characteristics by a CA1 Pyramidal Neuron Model

PubMed Central

Pissadaki, Eleftheria Kyriaki; Sidiropoulou, Kyriaki; Reczko, Martin; Poirazi, Panayiota

2010-01-01

The in vivo activity of CA1 pyramidal neurons alternates between regular spiking and bursting, but how these changes affect information processing remains unclear. Using a detailed CA1 pyramidal neuron model, we investigate how timing and spatial arrangement variations in synaptic inputs to the distal and proximal dendritic layers influence the information content of model responses. We find that the temporal delay between activation of the two layers acts as a switch between excitability modes: short delays induce bursting while long delays decrease firing. For long delays, the average firing frequency of the model response discriminates spatially clustered from diffused inputs to the distal dendritic tree. For short delays, the onset latency and inter-spike-interval succession of model responses can accurately classify input signals as temporally close or distant and spatially clustered or diffused across different stimulation protocols. These findings suggest that a CA1 pyramidal neuron may be capable of encoding and transmitting presynaptic spatiotemporal information about the activity of the entorhinal cortex-hippocampal network to higher brain regions via the selective use of either a temporal or a rate code. PMID:21187899

Terminal Field and Firing Selectivity of Cholecystokinin-Expressing Interneurons in the Hippocampal CA3 Area

PubMed Central

Lasztóczi, Bálint; Tukker, John J.; Somogyi, Peter; Klausberger, Thomas

2015-01-01

Hippocampal oscillations reflect coordinated neuronal activity on many timescales. Distinct types of GABAergic interneuron participate in the coordination of pyramidal cells over different oscillatory cycle phases. In the CA3 area, which generates sharp waves and gamma oscillations, the contribution of identified GABAergic neurons remains to be defined. We have examined the firing of a family of cholecystokinin-expressing interneurons during network oscillations in urethane-anesthetized rats and compared them with firing of CA3 pyramidal cells. The position of the terminals of individual visualized interneurons was highly diverse, selective, and often spatially coaligned with either the entorhinal or the associational inputs to area CA3. The spike timing in relation to theta and gamma oscillations and sharp waves was correlated with the innervated pyramidal cell domain. Basket and dendritic-layer-innervating interneurons receive entorhinal and associational inputs and preferentially fire on the ascending theta phase, when pyramidal cell assemblies emerge. Perforant-path-associated cells, driven by recurrent collaterals of pyramidal cells fire on theta troughs, when established pyramidal cell assemblies are most active. In the CA3 area, slow and fast gamma oscillations occurred on opposite theta oscillation phases. Perforant-path-associated and some COUP-TFII-positive interneurons are strongly coupled to both fast and slow gamma oscillations, but basket and dendritic-layer-innervating cells are weakly coupled to fast gamma oscillations only. During sharp waves, different interneuron types are activated, inhibited, or remain unaffected. We suggest that specialization in pyramidal cell domain and glutamatergic input-specific operations, reflected in the position of GABAergic terminals, is the evolutionary drive underlying the diversity of cholecystokinin-expressing interneurons. PMID:22159120

New oxyfluorotellurates(IV): MTeO3F (M = FeIII, GaIII and CrIII).

PubMed

Laval, Jean Paul; Jennene Boukharrata, Nefla; Thomas, Philippe

2008-02-01

The crystal structures of the new isomorphous compounds iron(III) oxyfluorotellurate(IV), FeTeO(3)F, gallium(III) oxyfluorotellurate(IV), GaTeO(3)F, and chromium(III) oxyfluorotellurate(IV), CrTeO(3)F, consist of zigzag chains of MO(4)F(2) distorted octahedra alternately sharing O-O and F-F edges and connected via TeO(3) trigonal pyramids. A full O/F anionic ordering is observed and the electronic lone pair of the Te(IV) cation is stereochemically active.

Intracortical Microstimulation (ICMS) Activates Motor Cortex Layer 5 Pyramidal Neurons Mainly Transsynaptically.

PubMed

Hussin, Ahmed T; Boychuk, Jeffery A; Brown, Andrew R; Pittman, Quentin J; Teskey, G Campbell

2015-01-01

Intracortical microstimulation (ICMS) is a technique used for a number of purposes including the derivation of cortical movement representations (motor maps). Its application can activate the output layer 5 of motor cortex and can result in the elicitation of body movements depending upon the stimulus parameters used. The extent to which pyramidal tract projection neurons of the motor cortex are activated transsynaptically or directly by ICMS remains an open question. Given this uncertainty in the mode of activation, we used a preparation that combined patch clamp whole-cell recordings from single layer 5 pyramidal neurons and extracellular ICMS in slices of motor cortex as well as a standard in vivo mapping technique to ask how ICMS activated motor cortex pyramidal neurons. We measured changes in synaptic spike threshold and spiking rate to ICMS in vitro and movement threshold in vivo in the presence or absence of specific pharmacological blockers of glutamatergic (AMPA, NMDA and Kainate) receptors and GABAA receptors. With major excitatory and inhibitory synaptic transmission blocked (with DNQX, APV and bicuculline methiodide), we observed a significant increase in the ICMS current intensity required to elicit a movement in vivo as well as to the first spike and an 85% reduction in spiking responses in vitro. Subsets of neurons were still responsive after the synaptic block, especially at higher current intensities, suggesting a modest direct activation. Taken together our data indicate a mainly synaptic mode of activation to ICMS in layer 5 of rat motor cortex. Copyright © 2015 Elsevier Inc. All rights reserved.

Solvothermal syntheses and characterization of three new silver(I)/copper(I)-thioarsenates based on As{sup 2+}/As{sup 3+} ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Hua-Gang, E-mail: hgyao@gdpu.edu.cn; Guangdong Cosmetics Engineering & Technology Research Center, Zhongshan 528458; Tang, Cheng-Fei

2017-02-15

Three new silver(I)/copper(I)-thioarsenates KAgAs{sup II}S{sub 2} (1), RbCu{sub 2}As{sup III}S{sub 3} (2) and RbCu{sub 4}As{sup III}S{sub 4} (3) have been solvothermally synthesized and structurally characterized. 1 exhibits a two-dimensional anionic network built up by As−As bond connecting the left- and right-handed helical [AgS{sub 2}]{sup 4−} chains, and represents the first examples of thioarsenates(II). The structure of 2 consists of two kinds of helical [Cu{sub 2}S{sub 3}]{sup 4–} chains linked by the arsenic atoms to form double layers with rubidium ions between the layers. Compound 3 is built up of infinite [Cu{sub 2}S{sub 2}]{sup 2–} chain and layered [Cu{sub 6}As{sub 2}S{submore » 6}] linked to form a three-dimensional anionic framework, [Cu{sub 4}AsS{sub 4}]{sup –}, and containing channels in which the rubidium cations reside. The optical properties of 1–3 have been investigated by UV–vis spectroscopy. - Graphical abstract: Three new silver(I)/copper(I)-thioarsenates have been solvothermally synthesized and structurally characterized. 1 represents the first examples of thioarsenates(II) while compounds 2 and 3 possess noncondensed pyramidal AsS{sub 3}{sup 3–} unit.« less

Distinct GABAergic targets of feedforward and feedback connections between lower and higher areas of rat visual cortex.

PubMed

Gonchar, Yuri; Burkhalter, Andreas

2003-11-26

Processing of visual information is performed in different cortical areas that are interconnected by feedforward (FF) and feedback (FB) pathways. Although FF and FB inputs are excitatory, their influences on pyramidal neurons also depend on the outputs of GABAergic neurons, which receive FF and FB inputs. Rat visual cortex contains at least three different families of GABAergic neurons that express parvalbumin (PV), calretinin (CR), and somatostatin (SOM) (Gonchar and Burkhalter, 1997). To examine whether pathway-specific inhibition (Shao and Burkhalter, 1996) is attributable to distinct connections with GABAergic neurons, we traced FF and FB inputs to PV, CR, and SOM neurons in layers 1-2/3 of area 17 and the secondary lateromedial area in rat visual cortex. We found that in layer 2/3 maximally 2% of FF and FB inputs go to CR and SOM neurons. This contrasts with 12-13% of FF and FB inputs onto layer 2/3 PV neurons. Unlike inputs to layer 2/3, connections to layer 1, which contains CR but lacks SOM and PV somata, are pathway-specific: 21% of FB inputs go to CR neurons, whereas FF inputs to layer 1 and its CR neurons are absent. These findings suggest that FF and FB influences on layer 2/3 pyramidal neurons mainly involve disynaptic connections via PV neurons that control the spike outputs to axons and proximal dendrites. Unlike FF input, FB input in addition makes a disynaptic link via CR neurons, which may influence the excitability of distal pyramidal cell dendrites in layer 1.

The mammalian neocortex new pyramidal neuron: a new conception.

PubMed

Marín-Padilla, Miguel

2014-01-06

The new cerebral cortex (neocortex) and the new type of pyramidal neuron are mammalian innovations that have evolved for operating their increasing motor capabilities while essentially using analogous anatomical and neural makeups. The human neocortex starts to develop in 6-week-old embryos with the establishment of a primordial cortical organization, which resembles the primitive cortices of amphibian and reptiles. From the 8th to the 15th week of age, new pyramidal neurons, of ependymal origin, are progressively incorporated within this primordial cortex forming a cellular plate that divides its components into those above it (neocortex first layer) and those below it (neocortex subplate zone). From the 16th week of age to birth and postnatally, the new pyramidal neurons continue to elongate functionally their apical dendrite by adding synaptic membrane to incorporate the needed sensory information for operating its developing motor activities. The new pyramidal neuron' distinguishing feature is the capacity of elongating anatomically and functionally its apical dendrite (its main receptive surface) without losing its original attachment to first layer or the location of its soma and, hence, retaining its essential nature. The number of pyramidal cell functional strata established in the motor cortex increases and reflects each mammalian species motor capabilities: the hedgehog needs two pyramidal cell functional strata to carry out all its motor activities, the mouse 3, cat 4, primates 5 and humans 6. The presence of six pyramidal cell functional strata distinguish the human motor cortex from that of others primates. Homo sapiens represent a new evolutionary stage that have transformed his primate brain for operating his unique motor capabilities, such as speaking, writing, painting, sculpturing and thinking as a premotor activity. Words used in language are the motor expression of thoughts and represent sounds produced by maneuvering the column of expiratory air by coordinated motor quivering as it passes through the larynx, pharynx, mouth, tongue, and lips. Homo sapiens cerebrum has developed new motor centers to communicate mental thoughts (and/or intention) through motor actions.

Influence of Deposition Pressure on the Properties of Round Pyramid Textured a-Si:H Solar Cells for Maglev.

PubMed

Lee, Jaehyeong; Choi, Wonseok; Lee, Kyuil; Lee, Daedong; Kang, Hyunil

2016-05-01

HIT (Heterojunction with Intrinsic Thin-layer) photovoltaic cells is one of the highest efficiencies in the commercial solar cells. The pyramid texturization for reducing surface reflectance of HIT solar cells silicon wafers is widely used. For the low leakage current and high shunt of solar cells, the intrinsic amorphous silicon (a-Si:H) on substrate must be uniformly thick of pyramid structure. However, it is difficult to control the thickness in the traditional pyramid texturing process. Thus, we textured the intrinsic a-Si:H thin films with the round pyramidal structure by using HNO3, HF, and CH3COOH solution. The characteristics of round pyramid a-Si:H solar cells deposited at pressure of 500, 1000, 1500, and 2000 mTorr by PECVD (Plasma Enhanced Chemical Vapor Deposition) was investigated. The lifetime, open circuit voltage, fill factor and efficiency of a-Si:H solar cells were investigated with respect to various deposition pressure.

Layer 2/3 pyramidal cells in the medial prefrontal cortex moderate stress induced depressive behaviors

PubMed Central

Shrestha, Prerana; Mousa, Awni; Heintz, Nathaniel

2015-01-01

Major depressive disorder (MDD) is a prevalent illness that can be precipitated by acute or chronic stress. Studies of patients with Wolfram syndrome and carriers have identified Wfs1 mutations as causative for MDD. The medial prefrontal cortex (mPFC) is known to be involved in depression and behavioral resilience, although the cell types and circuits in the mPFC that moderate depressive behaviors in response to stress have not been determined. Here, we report that deletion of Wfs1 from layer 2/3 pyramidal cells impairs the ability of the mPFC to suppress stress-induced depressive behaviors, and results in hyperactivation of the hypothalamic–pituitary–adrenal axis and altered accumulation of important growth and neurotrophic factors. Our data identify superficial layer 2/3 pyramidal cells as critical for moderation of stress in the context of depressive behaviors and suggest that dysfunction in these cells may contribute to the clinical relationship between stress and depression. DOI: http://dx.doi.org/10.7554/eLife.08752.001 PMID:26371510

Distribution and function of HCN channels in the apical dendritic tuft of neocortical pyramidal neurons.

PubMed

Harnett, Mark T; Magee, Jeffrey C; Williams, Stephen R

2015-01-21

The apical tuft is the most remote area of the dendritic tree of neocortical pyramidal neurons. Despite its distal location, the apical dendritic tuft of layer 5 pyramidal neurons receives substantial excitatory synaptic drive and actively processes corticocortical input during behavior. The properties of the voltage-activated ion channels that regulate synaptic integration in tuft dendrites have, however, not been thoroughly investigated. Here, we use electrophysiological and optical approaches to examine the subcellular distribution and function of hyperpolarization-activated cyclic nucleotide-gated nonselective cation (HCN) channels in rat layer 5B pyramidal neurons. Outside-out patch recordings demonstrated that the amplitude and properties of ensemble HCN channel activity were uniform in patches excised from distal apical dendritic trunk and tuft sites. Simultaneous apical dendritic tuft and trunk whole-cell current-clamp recordings revealed that the pharmacological blockade of HCN channels decreased voltage compartmentalization and enhanced the generation and spread of apical dendritic tuft and trunk regenerative activity. Furthermore, multisite two-photon glutamate uncaging demonstrated that HCN channels control the amplitude and duration of synaptically evoked regenerative activity in the distal apical dendritic tuft. In contrast, at proximal apical dendritic trunk and somatic recording sites, the blockade of HCN channels decreased excitability. Dynamic-clamp experiments revealed that these compartment-specific actions of HCN channels were heavily influenced by the local and distributed impact of the high density of HCN channels in the distal apical dendritic arbor. The properties and subcellular distribution pattern of HCN channels are therefore tuned to regulate the interaction between integration compartments in layer 5B pyramidal neurons. Copyright © 2015 the authors 0270-6474/15/351024-14$15.00/0.

Laminar-specific distribution of zinc: evidence for presence of layer IV in forelimb motor cortex in the rat.

PubMed

Alaverdashvili, Mariam; Hackett, Mark J; Pickering, Ingrid J; Paterson, Phyllis G

2014-12-01

The rat is the most widely studied pre-clinical model system of various neurological and neurodegenerative disorders affecting hand function. Although brain injury to the forelimb region of the motor cortex in rats mostly induces behavioral abnormalities in motor control of hand movements, behavioral deficits in the sensory-motor domain are also observed. This questions the prevailing view that cortical layer IV, a recipient of sensory information from the thalamus, is absent in rat motor cortex. Because zinc-containing neurons are generally not found in pathways that run from the thalamus, an absence of zinc (Zn) in a cortical layer would be suggestive of sensory input from the thalamus. To test this hypothesis, we used synchrotron micro X-ray fluorescence imaging to measure Zn distribution across cortical layers. Zn maps revealed a heterogeneous layered Zn distribution in primary and secondary motor cortices of the forelimb region in the adult rat. Two wider bands with elevated Zn content were separated by a narrow band having reduced Zn content, and this was evident in two rat strains. The Zn distribution pattern was comparable to that in sensorimotor cortex, which is known to contain a well demarcated layer IV. Juxtaposition of Zn maps and the images of brain stained for Nissl bodies revealed a "Zn valley" in primary motor cortex, apparently starting at the ventral border of pyramidal layer III and ending at the close vicinity of layer V. This finding indicates the presence of a conspicuous cortical layer between layers III and V, i.e. layer IV, the presence of which previously has been disputed. The results have implications for the use of rat models to investigate human brain function and neuropathology, such as after stroke. The presence of layer IV in the forelimb region of the motor cortex suggests that therapeutic interventions used in rat models of motor cortex injury should target functional abnormalities in both motor and sensory domains. The finding is also critical for future investigation of the biochemical mechanisms through which therapeutic interventions can enhance neural plasticity, particularly through Zn dependent pathways. Copyright © 2014 Elsevier Inc. All rights reserved.

Laminar-specific distribution of zinc: Evidence for presence of layer IV in forelimb motor cortex in the rat

PubMed Central

Alaverdashvili, Mariam; Hackett, Mark J.; Pickering, Ingrid J.; Paterson, Phyllis G.

2015-01-01

The rat is the most widely studied pre-clinical model system of various neurological and neurodegenerative disorders affecting hand function. Although brain injury to the forelimb region of the motor cortex in rats mostly induces behavioral abnormalities in motor control of hand movements, behavioral deficits in the sensory-motor domain are also observed. This questions the prevailing view that cortical layer IV, a recipient of sensory information from the thalamus, is absent in rat motor cortex. Because zinc-containing neurons are generally not found in pathways that run from the thalamus, an absence of zinc (Zn) in a cortical layer would be suggestive of sensory input from the thalamus. To test this hypothesis, we used synchrotron micro X-ray fluorescence imaging to measure Zn distribution across cortical layers. Zn maps revealed a heterogeneous layered Zn distribution in primary and secondary motor cortices of the forelimb region in the adult rat. Two wider bands with elevated Zn content were separated by a narrow band having reduced Zn content, and this was evident in two rat strains. The Zn distribution pattern was comparable to that in sensorimotor cortex, which is known to contain a well demarcated layer IV. Juxtaposition of Zn maps and the images of brain stained for Nissl bodies revealed a “Zn valley” in primary motor cortex, apparently starting at the ventral border of pyramidal layer III and ending at the close vicinity of layer V. This finding indicates the presence of a conspicuous cortical layer between layers III and V, i.e. layer IV, the presence of which previously has been disputed. The results have implications for the use of rat models to investigate human brain function and neuropathology, such as after stroke. The presence of layer IV in the forelimb region of the motor cortex suggests that therapeutic interventions used in rat models of motor cortex injury should target functional abnormalities in both motor and sensory domains. The finding is also critical for future investigation of the biochemical mechanisms through which therapeutic interventions can enhance neural plasticity, particularly through Zn dependent pathways. PMID:25192655

Characterization of focal cortical dysplasia with balloon cells by layer-specific markers: Evidence for differential vulnerability of interneurons.

PubMed

Nakagawa, Julia M; Donkels, Catharina; Fauser, Susanne; Schulze-Bonhage, Andreas; Prinz, Marco; Zentner, Josef; Haas, Carola A

2017-04-01

Focal cortical dysplasia (FCD) is a major cause of pharmacoresistant focal epilepsy. Little is known about the pathomechanisms underlying the characteristic cytoarchitectural abnormalities associated with FCD. In the present study, a broad panel of markers identifying layer-specific neuron subpopulations was applied to characterize dyslamination and structural alterations in FCD with balloon cells (FCD 2b). Pan-neuronal neuronal nuclei (NeuN) and layer-specific protein expression (Reelin, Calbindin, Calretinin, SMI32 (nonphosphorylated neurofilament H), Parvalbumin, transducin-like enhancer protein 4 (TLE4), and Vimentin) was studied by immunohistochemistry on paraffin sections of FCD2b cases (n = 22) and was compared to two control groups with (n = 7) or without epilepsy (n = 4 postmortem cases). Total and layer-specific neuron densities were systematically quantified by cell counting considering age at surgery and brain region. We show that in FCD2b total neuron densities across all six cortical layers were not significantly different from controls. In addition, we present evidence that a basic laminar arrangement of layer-specific neuron subtypes was preserved despite the severe disturbance of cortical structure. SMI32-positive pyramidal neurons showed no significant difference in total numbers, but a reduction in layers III and V. The densities of supragranular Calbindin- and Calretinin-positive interneurons in layers II and III were not different from controls, whereas Parvalbumin-expressing interneurons, primarily located in layer IV, were significantly reduced in numbers when compared to control cases without epilepsy. In layer VI, the density of TLE4-positive projection neurons was significantly increased. Altogether, these data show that changes in cellular composition mainly affect deep cortical layers in FCD2b. The application of a broad panel of markers defining layer-specific neuronal subpopulations revealed that in FCD2b neuronal diversity and a basic laminar arrangement are maintained despite the severe disturbance of cytoarchitecture. Moreover, it showed that Parvalbumin-positive, inhibitory interneurons are highly vulnerable in contrast to other interneuron subtypes, possibly related to the epileptic condition. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

Tris(O-cyclo­hexyl dithio­carbonato-κS)anti­mony(III)

PubMed Central

Li, Wenkuan; Yin, Handong; Wen, Liyuan; Wang, Daqi

2009-01-01

In the mol­ecule of the title compound, [Sb(C7H11OS2)3], the anti­mony(III) is coordinated by the S atoms of three O-alkyl xanthate groups acting as monodentate ligands, forming a distorted trigonal-pyramidal coordination. PMID:21581504

Development of inhibitory synaptic inputs on layer 2/3 pyramidal neurons in the rat medial prefrontal cortex.

PubMed

Virtanen, Mari A; Lacoh, Claudia Marvine; Fiumelli, Hubert; Kosel, Markus; Tyagarajan, Shiva; de Roo, Mathias; Vutskits, Laszlo

2018-05-01

Inhibitory control of pyramidal neurons plays a major role in governing the excitability in the brain. While spatial mapping of inhibitory inputs onto pyramidal neurons would provide important structural data on neuronal signaling, studying their distribution at the single cell level is difficult due to the lack of easily identifiable anatomical proxies. Here, we describe an approach where in utero electroporation of a plasmid encoding for fluorescently tagged gephyrin into the precursors of pyramidal cells along with ionotophoretic injection of Lucifer Yellow can reliably and specifically detect GABAergic synapses on the dendritic arbour of single pyramidal neurons. Using this technique and focusing on the basal dendritic arbour of layer 2/3 pyramidal cells of the medial prefrontal cortex, we demonstrate an intense development of GABAergic inputs onto these cells between postnatal days 10 and 20. While the spatial distribution of gephyrin clusters was not affected by the distance from the cell body at postnatal day 10, we found that distal dendritic segments appeared to have a higher gephyrin density at later developmental stages. We also show a transient increase around postnatal day 20 in the percentage of spines that are carrying a gephyrin cluster, indicative of innervation by a GABAergic terminal. Since the precise spatial arrangement of synaptic inputs is an important determinant of neuronal responses, we believe that the method described in this work may allow a better understanding of how inhibition settles together with excitation, and serve as basics for further modelling studies focusing on the geometry of dendritic inhibition during development.

Age-related increase of sIAHP in prefrontal pyramidal cells of monkeys: relationship to cognition

PubMed Central

Luebke, Jennifer I.; Amatrudo, Joseph M.

2010-01-01

Reduced excitability, due to an increase in the slow afterhyperpolarization (and its underlying current sIAHP), occurs in CA1 pyramidal cells in aged cognitively-impaired, but not cognitively-unimpaired, rodents. We sought to determine whether similar age-related changes in the sIAHP occur in pyramidal cells in the rhesus monkey dorsolateral prefrontal cortex (dlPFC). Whole-cell patch-clamp recordings were obtained from layer 3 (L3) and layer 5 (L5) pyramidal cells in dlPFC slices prepared from young (9.6 ± 0.7 years old) and aged (22.3 ± 0.7 years old) behaviorally characterized subjects. The amplitude of the sIAHP was significantly greater in L3 (but not L5) cells from aged-impaired compared to both aged-unimpaired and young monkeys, which did not differ. Aged L3, but not L5, cells exhibited significantly increased action potential firing rates, but there was no relationship between sIAHP and firing rate. Thus, in monkey dlPFC L3 cells, an increase in sIAHP is associated with age-related cognitive decline; however, this increase is not associated with a reduction in excitability. PMID:20727620

The tufas of Pyramid Lake, Nevada

USGS Publications Warehouse

Benson, Larry V.

2004-01-01

Pyramid Lake is the site of some of the Earth's most spectacular tufa deposits. The Tufas are composed of calcium carbonate (CaCO3). The large tufa mounds, reef- and sheet-like tufas formed within Pyramid Lake, between 26,000 and 13,000 years (yr) ago, when the lake was part of pluvial Lake Lahontan. The mounds are composed of large interlocking spheres that contain multiple generations of a crystalline (thinolite) variety of tufa. Over time many of the mounds have fallen apart, exposing an internal network of tubes. The tubular structures are thought to have been created when springs discharged from the bottom of Pyramid Lake, supplying calcium that combined with carbonate dissolved in lake water to form the mounds. The reef- and sheet-like deposits contain pillow and pendant forms made up of a branching variety of tufa that often grades into dense layers or nodules. Dense layers of tufa also coat cobbles and boulders that were deposited in near-shore shallow-water areas. The thickest tufa deposits formed at lake-bottom sites of ground-water discharge and at overflow elevations1 where the lake was held at near-constant levels for long periods of time.

Cornu Ammonis Regions–Antecedents of Cortical Layers?

PubMed Central

Mercer, Audrey; Thomson, Alex M.

2017-01-01

Studying neocortex and hippocampus in parallel, we are struck by the similarities. All three to four layered allocortices and the six layered mammalian neocortex arise in the pallium. All receive and integrate multiple cortical and subcortical inputs, provide multiple outputs and include an array of neuronal classes. During development, each cell positions itself to sample appropriate local and distant inputs and to innervate appropriate targets. Simpler cortices had already solved the need to transform multiple coincident inputs into serviceable outputs before neocortex appeared in mammals. Why then do phylogenetically more recent cortices need multiple pyramidal cell layers? A simple answer is that more neurones can compute more complex functions. The dentate gyrus and hippocampal CA regions—which might be seen as hippocampal antecedents of neocortical layers—lie side by side, albeit around a tight bend. Were the millions of cells of rat neocortex arranged in like fashion, the surface area of the CA pyramidal cell layers would be some 40 times larger. Even if evolution had managed to fold this immense sheet into the space available, the distances between neurones that needed to be synaptically connected would be huge and to maintain the speed of information transfer, massive, myelinated fiber tracts would be needed. How much more practical to stack the “cells that fire and wire together” into narrow columns, while retaining the mechanisms underlying the extraordinary precision with which circuits form. This demonstrably efficient arrangement presents us with challenges, however, not the least being to categorize the baffling array of neuronal subtypes in each of five “pyramidal layers.” If we imagine the puzzle posed by this bewildering jumble of apical dendrites, basal dendrites and axons, from many different pyramidal and interneuronal classes, that is encountered by a late-arriving interneurone insinuating itself into a functional circuit, we can perhaps begin to understand why definitive classification, covering every aspect of each neurone's structure and function, is such a challenge. Here, we summarize and compare the development of these two cortices, the properties of their neurones, the circuits they form and the ordered, unidirectional flow of information from one hippocampal region, or one neocortical layer, to another. PMID:29018334

White emission from non-planar InGaN/GaN MQW LEDs grown on GaN template with truncated hexagonal pyramids.

PubMed

Lee, Ming-Lun; Yeh, Yu-Hsiang; Tu, Shang-Ju; Chen, P C; Lai, Wei-Chih; Sheu, Jinn-Kong

2015-04-06

Non-planar InGaN/GaN multiple quantum well (MQW) structures are grown on a GaN template with truncated hexagonal pyramids (THPs) featuring c-plane and r-plane surfaces. The THP array is formed by the regrowth of the GaN layer on a selective-area Si-implanted GaN template. Transmission electron microscopy shows that the InGaN/GaN epitaxial layers regrown on the THPs exhibit different growth rates and indium compositions of the InGaN layer between the c-plane and r-plane surfaces. Consequently, InGaN/GaN MQW light-emitting diodes grown on the GaN THP array emit multiple wavelengths approaching near white light.

InN island shape and its dependence on growth condition of molecular-beam epitaxy

NASA Astrophysics Data System (ADS)

Cao, Y. G.; Xie, M. H.; Liu, Y.; Ng, Y. F.; Wu, H. S.; Tong, S. Y.

2003-12-01

During molecular-beam epitaxy of InN films on GaN(0001) surface, three-dimensional (3D) islands are observed following an initial wetting layer formation. Depending on deposition condition, the 3D islands take different shapes. Pyramidal islands form when excess nitrogen fluxes are used, whereas pillar-shaped islands are obtained when excess indium fluxes are employed. The pillar-shaped islands are identified to represent the equilibrium shape, whereas the pyramidal ones are limited by kinetics. As the size of islands increases, their aspect ratio shows a decreasing trend, which is attributed to a gradual relaxation of strain in the layer by defects.

How a (sub)Cellular Coincidence Detection Mechanism Featuring Layer-5 Pyramidal Cells May Help Produce Various Visual Phenomena.

PubMed

Bachmann, Talis

2015-01-01

Perceptual phenomena such as spatio-temporal illusions and masking are typically explained by psychological (cognitive) processing theories or large-scale neural theories involving inter-areal connectivity and neural circuits comprising of hundreds or more interconnected single cells. Subcellular mechanisms are hardly used for such purpose. Here, a mechanistic theoretical view is presented on how a subcellular brain mechanism of integration of presynaptic signals that arrive at different compartments of layer-5 pyramidal neurons could explain a couple of spatiotemporal visual-phenomenal effects unfolding along very brief time intervals within the range of the sub-second temporal scale.

Postnatal development of A-type and Kv1- and Kv2-mediated potassium channel currents in neocortical pyramidal neurons

PubMed Central

Guan, Dongxu; Horton, Leslie R.; Armstrong, William E.

2011-01-01

Potassium channels regulate numerous aspects of neuronal excitability, and several voltage-gated K+ channel subunits have been identified in pyramidal neurons of rat neocortex. Previous studies have either considered the development of outward current as a whole or divided currents into transient, A-type and persistent, delayed rectifier components but did not differentiate between current components defined by α-subunit type. To facilitate comparisons of studies reporting K+ currents from animals of different ages and to understand the functional roles of specific current components, we characterized the postnatal development of identified Kv channel-mediated currents in pyramidal neurons from layers II/III from rat somatosensory cortex. Both the persistent/slowly inactivating and transient components of the total K+ current increased in density with postnatal age. We used specific pharmacological agents to test the relative contributions of putative Kv1- and Kv2-mediated currents (100 nM α-dendrotoxin and 600 nM stromatoxin, respectively). A combination of voltage protocol, pharmacology, and curve fitting was used to isolate the rapidly inactivating A-type current. We found that the density of all identified current components increased with postnatal age, approaching a plateau at 3–5 wk. We found no significant changes in the relative proportions or kinetics of any component between postnatal weeks 1 and 5, except that the activation time constant for A-type current was longer at 1 wk. The putative Kv2-mediated component was the largest at all ages. Immunocytochemistry indicated that protein expression for Kv4.2, Kv4.3, Kv1.4, and Kv2.1 increased between 1 wk and 4–5 wk of age. PMID:21451062

Postnatal development of A-type and Kv1- and Kv2-mediated potassium channel currents in neocortical pyramidal neurons.

PubMed

Guan, Dongxu; Horton, Leslie R; Armstrong, William E; Foehring, Robert C

2011-06-01

Potassium channels regulate numerous aspects of neuronal excitability, and several voltage-gated K(+) channel subunits have been identified in pyramidal neurons of rat neocortex. Previous studies have either considered the development of outward current as a whole or divided currents into transient, A-type and persistent, delayed rectifier components but did not differentiate between current components defined by α-subunit type. To facilitate comparisons of studies reporting K(+) currents from animals of different ages and to understand the functional roles of specific current components, we characterized the postnatal development of identified Kv channel-mediated currents in pyramidal neurons from layers II/III from rat somatosensory cortex. Both the persistent/slowly inactivating and transient components of the total K(+) current increased in density with postnatal age. We used specific pharmacological agents to test the relative contributions of putative Kv1- and Kv2-mediated currents (100 nM α-dendrotoxin and 600 nM stromatoxin, respectively). A combination of voltage protocol, pharmacology, and curve fitting was used to isolate the rapidly inactivating A-type current. We found that the density of all identified current components increased with postnatal age, approaching a plateau at 3-5 wk. We found no significant changes in the relative proportions or kinetics of any component between postnatal weeks 1 and 5, except that the activation time constant for A-type current was longer at 1 wk. The putative Kv2-mediated component was the largest at all ages. Immunocytochemistry indicated that protein expression for Kv4.2, Kv4.3, Kv1.4, and Kv2.1 increased between 1 wk and 4-5 wk of age.

Probes for multidimensional nanospectroscopic imaging and methods of fabrication thereof

DOEpatents

Weber-Bargioni, Alexander; Cabrini, Stefano; Bao, Wei; Melli, Mauro; Yablonovitch, Eli; Schuck, Peter J

2015-03-17

This disclosure provides systems, methods, and apparatus related to probes for multidimensional nanospectroscopic imaging. In one aspect, a method includes providing a transparent tip comprising a dielectric material. A four-sided pyramidal-shaped structure is formed at an apex of the transparent tip using a focused ion beam. Metal layers are deposited over two opposing sides of the four-sided pyramidal-shaped structure.

Laminar activity in the hippocampus and entorhinal cortex related to novelty and episodic encoding

PubMed Central

Maass, Anne; Schütze, Hartmut; Speck, Oliver; Yonelinas, Andrew; Tempelmann, Claus; Heinze, Hans-Jochen; Berron, David; Cardenas-Blanco, Arturo; Brodersen, Kay H.; Enno Stephan, Klaas; Düzel, Emrah

2014-01-01

The ability to form long-term memories for novel events depends on information processing within the hippocampus (HC) and entorhinal cortex (EC). The HC–EC circuitry shows a quantitative segregation of anatomical directionality into different neuronal layers. Whereas superficial EC layers mainly project to dentate gyrus (DG), CA3 and apical CA1 layers, HC output is primarily sent from pyramidal CA1 layers and subiculum to deep EC layers. Here we utilize this directionality information by measuring encoding activity within HC/EC subregions with 7 T high resolution functional magnetic resonance imaging (fMRI). Multivariate Bayes decoding within HC/EC subregions shows that processing of novel information most strongly engages the input structures (superficial EC and DG/CA2–3), whereas subsequent memory is more dependent on activation of output regions (deep EC and pyramidal CA1). This suggests that while novelty processing is strongly related to HC–EC input pathways, the memory fate of a novel stimulus depends more on HC–EC output. PMID:25424131

A golgi study of the optic tectum of the tegu lizard, Tupinambis nigropunctatus.

PubMed

Butler, A B; Ebbesson, O E

1975-06-01

The dendritic patterns of cells in the optic tectum of the tegu lizard, Tupinambis nigropunctatus, were analyzed with the Ramon-Moliner modification of the Golgi-Cox technique. Cell types were compared with those described by other authors in the tectum of other reptiles; particular comparisons of our results were made with the description of cell types in the chameleon (Ramń, 1896), as the latter is the most complete analysis in the literature. The periventricular gray layers 3 and 5 consist primarily of two cell types--piriform or pyramidal shaped cells and horizontal cells. Cells in the medial portion of the tectum, in an area coextensive with the bilateral spinal projection zone, possess dendrites that extend across the midline. The latter cells have either fusiform or pyramidal shaped somas. The central white zone, layer 6, contains fibers, large fusiform or pyramidal shaped cells, fusiform cells, and small horizontal cells. The central gray zone, layer 7, is composed predominately of fusiform cells which have dendrites extending to the superficial optic layers, large polygonal cells, and horizontal cells. The superficial gray and white layers, layers 8-13, contain polygonal, fusiform, stellate, and horizontal elements. Layer 14 is composed solely of afferent optic tract fibers. Several differences in the occurrence and distribution of cell types between the tegu and the other reptiles studied are noted. Additionally, the laminar distribution of retinal, tectotectal, telencephalic, and spinal projections in the tegutectum can be related to the distribution of cell types, and those cells which may be postsynaptic to specific inputs can be identified. The highly differentiated laminar structure of the reptilian optic tectum, both in regard to cell type and to afferent and efferent connections, may serve as a model for studying some functional properties of lamination common to cortical structures.

Effect of the environment on the dendritic morphology of the rat auditory cortex

PubMed Central

Bose, Mitali; Muñoz-Llancao, Pablo; Roychowdhury, Swagata; Nichols, Justin A.; Jakkamsetti, Vikram; Porter, Benjamin; Byrapureddy, Rajasekhar; Salgado, Humberto; Kilgard, Michael P.; Aboitiz, Francisco; Dagnino-Subiabre, Alexies; Atzori, Marco

2010-01-01

The present study aimed to identify morphological correlates of environment-induced changes at excitatory synapses of the primary auditory cortex (A1). We used the Golgi-Cox stain technique to compare pyramidal cells dendritic properties of Sprague-Dawley rats exposed to different environmental manipulations. Sholl analysis, dendritic length measures, and spine density counts were used to monitor the effects of sensory deafness and an auditory version of environmental enrichment (EE). We found that deafness decreased apical dendritic length leaving basal dendritic length unchanged, whereas EE selectively increased basal dendritic length without changing apical dendritic length. On the contrary, deafness decreased while EE increased spine density in both basal and apical dendrites of A1 layer 2/3 (LII/III) neurons. To determine whether stress contributed to the observed morphological changes in A1, we studied neural morphology in a restraint-induced model that lacked behaviorally relevant acoustic cues. We found that stress selectively decreased apical dendritic length in the auditory but not in the visual primary cortex. Similar to the acoustic manipulation, stress-induced changes in dendritic length possessed a layer specific pattern displaying LII/III neurons from stressed animals with normal apical dendrites but shorter basal dendrites, while infragranular neurons (layers V and VI) displayed shorter apical dendrites but normal basal dendrites. The same treatment did not induce similar changes in the visual cortex, demonstrating that the auditory cortex is an exquisitely sensitive target of neocortical plasticity, and that prolonged exposure to different acoustic as well as emotional environmental manipulation may produce specific changes in dendritic shape and spine density. PMID:19771593

Cell structure and function in the visual cortex of the cat

PubMed Central

Kelly, J. P.; Van Essen, D. C.

1974-01-01

1. The organization of the visual cortex was studied with a technique that allows one to determine the physiology and morphology of individual cells. Micro-electrodes filled with the fluorescent dye Procion yellow were used to record intracellularly from cells in area 17 of the cat. The visual receptive field of each neurone was classified as simple, complex, or hypercomplex, and the cell was then stained by the iontophoretic injection of dye. 2. Fifty neurones were successfully examined in this way, and their structural features were compared to the varieties of cell types seen in Golgi preparations of area 17. The majority of simple units were stellate cells, whereas the majority of complex and hypercomplex units were pyramidal cells. Several neurones belonged to less common morphological types, such as double bouquet cells. Simple cells were concentrated in layer IV, hypercomplex cells in layer II + III, and complex cells in layers II + III, V and VI. 3. Electrically inexcitable cells that had high resting potentials but no impulse activity were stained and identified as glial cells. Glial cells responded to visual stimuli with slow graded depolarizations, and many of them showed a preference for a stimulus orientation similar to the optimal orientation for adjacent neurones. 4. The results show that there is a clear, but not absolute correlation between the major structural and functional classes of cells in the visual cortex. This approach, linking the physiological properties of a single cell to a given morphological type, will help in furthering our understanding of the cerebral cortex. ImagesPlate 4Plate 1Plate 2Plate 3 PMID:4136579

Phencyclidine-induced Loss of Asymmetric Spine Synapses in Rodent Prefrontal Cortex is Reversed by Acute and Chronic Treatment with Olanzapine

PubMed Central

Elsworth, John D; Morrow, Bret A; Hajszan, Tibor; Leranth, Csaba; Roth, Robert H

2011-01-01

Enduring cognitive deficits exist in schizophrenic patients, long-term abusers of phencyclidine (PCP), as well as in animal PCP models of schizophrenia. It has been suggested that cognitive performance and memory processes are coupled with remodeling of pyramidal dendritic spine synapses in prefrontal cortex (PFC), and that reduced spine density and number of spine synapses in the medial PFC of PCP-treated rats may potentially underlie, at least partially, the cognitive dysfunction previously observed in this animal model. The present data show that the decrease in number of asymmetric (excitatory) spine synapses in layer II/III of PFC, previously noted at 1-week post PCP treatment also occurs, to a lesser degree, in layer V. The decrease in the number of spine synapses in layer II/III was sustained and persisted for at least 4 weeks, paralleling the observed cognitive deficits. Both acute and chronic treatment with the atypical antipsychotic drug, olanzapine, starting at 1 week after PCP treatment at doses that restore cognitive function, reversed the asymmetric spine synapse loss in PFC of PCP-treated rats. Olanzapine had no significant effect on spine synapse number in saline-treated controls. These studies demonstrate that the effect of PCP on asymmetric spine synapse number in PFC lasts at least 4 weeks in this model. This spine synapse loss in PFC is reversed by acute treatment with olanzapine, and this reversal is maintained by chronic oral treatment, paralleling the time course of the restoration of the dopamine deficit, and normalization of cognitive function produced by olanzapine. PMID:21677652

Independent components of neural activity carry information on individual populations.

PubMed

Głąbska, Helena; Potworowski, Jan; Łęski, Szymon; Wójcik, Daniel K

2014-01-01

Local field potential (LFP), the low-frequency part of the potential recorded extracellularly in the brain, reflects neural activity at the population level. The interpretation of LFP is complicated because it can mix activity from remote cells, on the order of millimeters from the electrode. To understand better the relation between the recordings and the local activity of cells we used a large-scale network thalamocortical model to compute simultaneous LFP, transmembrane currents, and spiking activity. We used this model to study the information contained in independent components obtained from the reconstructed Current Source Density (CSD), which smooths transmembrane currents, decomposed further with Independent Component Analysis (ICA). We found that the three most robust components matched well the activity of two dominating cell populations: superior pyramidal cells in layer 2/3 (rhythmic spiking) and tufted pyramids from layer 5 (intrinsically bursting). The pyramidal population from layer 2/3 could not be well described as a product of spatial profile and temporal activation, but by a sum of two such products which we recovered in two of the ICA components in our analysis, which correspond to the two first principal components of PCA decomposition of layer 2/3 population activity. At low noise one more cell population could be discerned but it is unlikely that it could be recovered in experiment given typical noise ranges.

Independent Components of Neural Activity Carry Information on Individual Populations

PubMed Central

Głąbska, Helena; Potworowski, Jan; Łęski, Szymon; Wójcik, Daniel K.

2014-01-01

Local field potential (LFP), the low-frequency part of the potential recorded extracellularly in the brain, reflects neural activity at the population level. The interpretation of LFP is complicated because it can mix activity from remote cells, on the order of millimeters from the electrode. To understand better the relation between the recordings and the local activity of cells we used a large-scale network thalamocortical model to compute simultaneous LFP, transmembrane currents, and spiking activity. We used this model to study the information contained in independent components obtained from the reconstructed Current Source Density (CSD), which smooths transmembrane currents, decomposed further with Independent Component Analysis (ICA). We found that the three most robust components matched well the activity of two dominating cell populations: superior pyramidal cells in layer 2/3 (rhythmic spiking) and tufted pyramids from layer 5 (intrinsically bursting). The pyramidal population from layer 2/3 could not be well described as a product of spatial profile and temporal activation, but by a sum of two such products which we recovered in two of the ICA components in our analysis, which correspond to the two first principal components of PCA decomposition of layer 2/3 population activity. At low noise one more cell population could be discerned but it is unlikely that it could be recovered in experiment given typical noise ranges. PMID:25153730

One-step Maskless Fabrication and Optical Characterization of Silicon Surfaces with Antireflective Properties and a White Color Appearance

PubMed Central

Schneider, Ling; Feidenhans’l, Nikolaj A.; Telecka, Agnieszka; Taboryski, Rafael J.

2016-01-01

We report a simple one-step maskless fabrication of inverted pyramids on silicon wafers by reactive ion etching. The fabricated surface structures exhibit excellent anti-reflective properties: The total reflectance of the nano inverted pyramids fabricated by our method can be as low as 12% without any anti-reflective layers, and down to only 0.33% with a silicon nitride coating. The results from angle resolved scattering measurements indicate that the existence of triple reflections is responsible for the reduced reflectance. The surfaces with the nano inverted pyramids also exhibit a distinct milky white color. PMID:27725703

Tunable-Sensitivity flexible pressure sensor based on graphene transparent electrode

NASA Astrophysics Data System (ADS)

Luo, Shi; Yang, Jun; Song, Xuefen; Zhou, Xi; Yu, Leyong; Sun, Tai; Yu, Chongsheng; Huang, Deping; Du, Chunlei; Wei, Dapeng

2018-07-01

Tunable-sensitivity and flexibility are considered as two crucial characteristics for future pressure sensors or electronic skins. By the theoretical calculation model, we simulated the relationship curve between the sensitivity and PDMS pyramids with different spacings, and found that the spacing of pyramids is a main factor to affect the sensitivity of the capacitance pressure sensor. Furthermore, we fabricated the capacitance pressure sensors using graphene electrodes and the PDMS pyramid dielectric layers with different spacings. The measurement data were consistent with the simulation results that the sensitivity increases with the spacing of pyramids. In addition, graphene electrode exhibits prefect flexibility and reliability, while the ITO electrode would be destroyed rapidly after bending. These graphene pressure sensors exhibit the potential in the application in the wearable products for monitoring breath, pulse, and other physiological signals.

Testing the pyramid truth wavefront sensor for NFIRAOS in the lab

NASA Astrophysics Data System (ADS)

Mieda, Etsuko; Rosensteiner, Matthias; van Kooten, Maaike; Veran, Jean-Pierre; Lardiere, Olivier; Herriot, Glen

2016-07-01

For today and future adaptive optics observations, sodium laser guide stars (LGSs) are crucial; however, the LGS elongation problem due to the sodium layer has to be compensated, in particular for extremely large telescopes. In this paper, we describe the concept of truth wavefront sensing as a solution and present its design using a pyramid wavefront sensor (PWFS) to improve NFIRAOS (Narrow Field InfraRed Adaptive Optics System), the first light adaptive optics system for Thirty Meter Telescope. We simulate and test the truth wavefront sensor function under a controlled environment using the HeNOS (Herzberg NFIRAOS Optical Simulator) bench, a scaled-down NFIRAOS bench at NRC-Herzberg. We also touch on alternative pyramid component options because despite recent high demands for PWFSs, we suffer from the lack of pyramid supplies due to engineering difficulties.

Exciton binding energy in a pyramidal quantum dot

NASA Astrophysics Data System (ADS)

Anitha, A.; Arulmozhi, M.

2018-05-01

The effects of spatially dependent effective mass, non-parabolicity of the conduction band and dielectric screening function on exciton binding energy in a pyramid-shaped quantum dot of GaAs have been investigated by variational method as a function of base width of the pyramid. We have assumed that the pyramid has a square base with area a× a and height of the pyramid H=a/2. The trial wave function of the exciton has been chosen according to the even mirror boundary condition, i.e. the wave function of the exciton at the boundary could be non-zero. The results show that (i) the non-parabolicity of the conduction band affects the light hole (lh) and heavy hole (hh) excitons to be more bound than that with parabolicity of the conduction band, (ii) the dielectric screening function (DSF) affects the lh and hh excitons to be more bound than that without the DSF and (iii) the spatially dependent effective mass (SDEM) affects the lh and hh excitons to be less bound than that without the SDEM. The combined effects of DSF and SDEM on exciton binding energy have also been calculated. The results are compared with those available in the literature.

Localization of the cannabinoid CB1 receptor and the 2-AG synthesizing (DAGLα) and degrading (MAGL, FAAH) enzymes in cells expressing the Ca2+-binding proteins calbindin, calretinin, and parvalbumin in the adult rat hippocampus

PubMed Central

Rivera, Patricia; Arrabal, Sergio; Cifuentes, Manuel; Grondona, Jesús M.; Pérez-Martín, Margarita; Rubio, Leticia; Vargas, Antonio; Serrano, Antonia; Pavón, Francisco J.; Suárez, Juan; Rodríguez de Fonseca, Fernando

2014-01-01

The retrograde suppression of the synaptic transmission by the endocannabinoid sn-2-arachidonoylglycerol (2-AG) is mediated by the cannabinoid CB1 receptors and requires the elevation of intracellular Ca2+ and the activation of specific 2-AG synthesizing (i.e., DAGLα) enzymes. However, the anatomical organization of the neuronal substrates that express 2-AG/CB1 signaling system-related molecules associated with selective Ca2+-binding proteins (CaBPs) is still unknown. For this purpose, we used double-label immunofluorescence and confocal laser scanning microscopy for the characterization of the expression of the 2-AG/CB1 signaling system (CB1 receptor, DAGLα, MAGL, and FAAH) and the CaBPs calbindin D28k, calretinin, and parvalbumin in the rat hippocampus. CB1, DAGLα, and MAGL labeling was mainly localized in fibers and neuropil, which were differentially organized depending on the hippocampal CaBPs-expressing cells. CB+1 fiber terminals localized in all hippocampal principal cell layers were tightly attached to calbindin+ cells (granular and pyramidal neurons), and calretinin+ and parvalbumin+ interneurons. DAGLα neuropil labeling was selectively found surrounding calbindin+ principal cells in the dentate gyrus and CA1, and in the calretinin+ and parvalbumin+ interneurons in the pyramidal cell layers of the CA1/3 fields. MAGL+ terminals were only observed around CA1 calbindin+ pyramidal cells, CA1/3 calretinin+ interneurons and CA3 parvalbumin+ interneurons localized in the pyramidal cell layers. Interestingly, calbindin+ pyramidal cells expressed FAAH specifically in the CA1 field. The identification of anatomically related-neuronal substrates that expressed 2-AG/CB1 signaling system and selective CaBPs should be considered when analyzing the cannabinoid signaling associated with hippocampal functions. PMID:25018703

Characterization of neuronal intrinsic properties and synaptic transmission in layer I of anterior cingulate cortex from adult mice

PubMed Central

2012-01-01

The neurons in neocortex layer I (LI) provide inhibition to the cortical networks. Despite increasing use of mice for the study of brain functions, few studies were reported about mouse LI neurons. In the present study, we characterized intrinsic properties of LI neurons of the anterior cingulate cortex (ACC), a key cortical area for sensory and cognitive functions, by using whole-cell patch clamp recording approach. Seventy one neurons in LI and 12 pyramidal neurons in LII/III were recorded. Although all of the LI neurons expressed continuous adapting firing characteristics, the unsupervised clustering results revealed five groups in the ACC, including: Spontaneous firing neurons; Delay-sAHP neurons, Delay-fAHP neurons, and two groups of neurons with ADP, named ADP1 and ADP2, respectively. Using pharmacological approaches, we found that LI neurons received both excitatory (mediated by AMPA, kainate and NMDA receptors), and inhibitory inputs (which were mediated by GABAA receptors). Our studies provide the first report characterizing the electrophysiological properties of neurons in LI of the ACC from adult mice. PMID:22818293

Neurofilament protein is differentially distributed in subpopulations of corticocortical projection neurons in the macaque monkey visual pathways

NASA Technical Reports Server (NTRS)

Hof, P. R.; Ungerleider, L. G.; Webster, M. J.; Gattass, R.; Adams, M. M.; Sailstad, C. A.; Morrison, J. H.; Bloom, F. E. (Principal Investigator)

1996-01-01

Previous studies of the primate cerebral cortex have shown that neurofilament protein is present in pyramidal neuron subpopulations displaying specific regional and laminar distribution patterns. In order to characterize further the neurochemical phenotype of the neurons furnishing feedforward and feedback pathways in the visual cortex of the macaque monkey, we performed an analysis of the distribution of neurofilament protein in corticocortical projection neurons in areas V1, V2, V3, V3A, V4, and MT. Injections of the retrogradely transported dyes Fast Blue and Diamidino Yellow were placed within areas V4 and MT, or in areas V1 and V2, in 14 adult rhesus monkeys, and the brains of these animals were processed for immunohistochemistry with an antibody to nonphosphorylated epitopes of the medium and heavy molecular weight subunits of the neurofilament protein. Overall, there was a higher proportion of neurons projecting from areas V1, V2, V3, and V3A to area MT that were neurofilament protein-immunoreactive (57-100%), than to area V4 (25-36%). In contrast, feedback projections from areas MT, V4, and V3 exhibited a more consistent proportion of neurofilament protein-containing neurons (70-80%), regardless of their target areas (V1 or V2). In addition, the vast majority of feedback neurons projecting to areas V1 and V2 were located in layers V and VI in areas V4 and MT, while they were observed in both supragranular and infragranular layers in area V3. The laminar distribution of feedforward projecting neurons was heterogeneous. In area V1, Meynert and layer IVB cells were found to project to area MT, while neurons projecting to area V4 were particularly dense in layer III within the foveal representation. In area V2, almost all neurons projecting to areas MT or V4 were located in layer III, whereas they were found in both layers II-III and V-VI in areas V3 and V3A. These results suggest that neurofilament protein identifies particular subpopulations of corticocortically projecting neurons with distinct regional and laminar distribution in the monkey visual system. It is possible that the preferential distribution of neurofilament protein within feedforward connections to area MT and all feedback projections is related to other distinctive properties of these corticocortical projection neurons.

Defined types of cortical interneurone structure space and spike timing in the hippocampus

PubMed Central

Somogyi, Peter; Klausberger, Thomas

2005-01-01

The cerebral cortex encodes, stores and combines information about the internal and external environment in rhythmic activity of multiple frequency ranges. Neurones of the cortex can be defined, recognized and compared on the comprehensive application of the following measures: (i) brain area- and cell domain-specific distribution of input and output synapses, (ii) expression of molecules involved in cell signalling, (iii) membrane and synaptic properties reflecting the expression of membrane proteins, (iv) temporal structure of firing in vivo, resulting from (i)–(iii). Spatial and temporal measures of neurones in the network reflect an indivisible unity of evolutionary design, i.e. neurones do not have separate structure or function. The blueprint of this design is most easily accessible in the CA1 area of the hippocampus, where a relatively uniform population of pyramidal cells and their inputs follow an instantly recognizable laminated pattern and act within stereotyped network activity patterns. Reviewing the cell types and their spatio-temporal interactions, we suggest that CA1 pyramidal cells are supported by at least 16 distinct types of GABAergic neurone. During a given behaviour-contingent network oscillation, interneurones of a given type exhibit similar firing patterns. During different network oscillations representing two distinct brain states, interneurones of the same class show different firing patterns modulating their postsynaptic target-domain in a brain-state-dependent manner. These results suggest roles for specific interneurone types in structuring the activity of pyramidal cells via their respective target domains, and accurately timing and synchronizing pyramidal cell discharge, rather than providing generalized inhibition. Finally, interneurones belonging to different classes may fire preferentially at distinct time points during a given oscillation. As different interneurones innervate distinct domains of the pyramidal cells, the different compartments will receive GABAergic input differentiated in time. Such a dynamic, spatio-temporal, GABAergic control, which evolves distinct patterns during different brain states, is ideally suited to regulating the input integration of individual pyramidal cells contributing to the formation of cell assemblies and representations in the hippocampus and, probably, throughout the cerebral cortex. PMID:15539390

High In-content InGaN nano-pyramids: Tuning crystal homogeneity by optimized nucleation of GaN seeds

NASA Astrophysics Data System (ADS)

Bi, Zhaoxia; Gustafsson, Anders; Lenrick, Filip; Lindgren, David; Hultin, Olof; Wallenberg, L. Reine; Ohlsson, B. Jonas; Monemar, Bo; Samuelson, Lars

2018-01-01

Uniform arrays of submicron hexagonal InGaN pyramids with high morphological and material homogeneity, reaching an indium composition of 20%, are presented in this work. The pyramids were grown by selective area metal-organic vapor phase epitaxy and nucleated from small openings in a SiN mask. The growth selectivity was accurately controlled with diffusion lengths of the gallium and indium species, more than 1 μm on the SiN surface. High material homogeneity of the pyramids was achieved by inserting a precisely formed GaN pyramidal seed prior to InGaN growth, leading to the growth of well-shaped InGaN pyramids delimited by six equivalent {" separators="| 10 1 ¯ 1 } facets. Further analysis reveals a variation in the indium composition to be mediated by competing InGaN growth on two types of crystal planes, {" separators="| 10 1 ¯ 1 } and (0001). Typically, the InGaN growth on {" separators="| 10 1 ¯ 1 } planes is much slower than on the (0001) plane. The formation of the (0001) plane and the growth of InGaN on it were found to be dependent on the morphology of the GaN seeds. We propose growth of InGaN pyramids seeded by {" separators="| 10 1 ¯ 1 }-faceted GaN pyramids as a mean to avoid InGaN material grown on the otherwise formed (0001) plane, leading to a significant reduction of variations in the indium composition in the InGaN pyramids. The InGaN pyramids in this work can be used as a high-quality template for optoelectronic devices having indium-rich active layers, with a potential of reaching green, yellow, and red emissions for LEDs.

Short-term repeated corticosterone administration enhances glutamatergic but not GABAergic transmission in the rat motor cortex.

PubMed

Kula, Joanna; Blasiak, Anna; Czerw, Anna; Tylko, Grzegorz; Sowa, Joanna; Hess, Grzegorz

2016-04-01

It has been demonstrated that stress impairs performance of skilled reaching and walking tasks in rats due to the action of glucocorticoids involved in the stress response. Skilled reaching and walking are controlled by the primary motor cortex (M1); however, it is not known whether stress-related impairments in skilled motor tasks are related to functional and/or structural alterations within the M1. We studied the effects of single and repeated injections of corticosterone (twice daily for 7 days) on spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and sIPSCs) recorded from layer II/III pyramidal neurons in ex vivo slices of the M1, prepared 2 days after the last administration of the hormone. We also measured the density of dendritic spines on pyramidal cells and the protein levels of selected subunits of AMPA, NMDA, and GABAA receptors after repeated corticosterone administration. Repeatedly administered corticosterone induced an increase in the frequency but not in the amplitude of sEPSCs, while a single administration had no effect on the recorded excitatory currents. The frequency and amplitude of sIPSCs as well as the excitability of pyramidal cells were changed neither after single nor after repeated corticosterone administration. Treatment with corticosterone for 7 days did not modify the density of dendritic spines on pyramidal neurons. Corticosterone influenced neither the protein levels of GluA1, GluA2, GluN1, GluN2A, and GluN2B subunits of glutamate receptors nor those of α1, β2, and γ2 subunits of the GABAA receptor. The increase in sEPSCs frequency induced by repeated corticosterone administration faded out within 7 days. These data indicate that prolonged administration of exogenous corticosterone selectively and reversibly enhances glutamatergic, but not GABAergic transmission in the rat motor cortex. Our results suggest that corticosterone treatment results in an enhancement of spontaneous glutamate release from presynaptic terminals in the M1 and thereby uncovers a potential mechanism underlying stress-induced motor functions impairment.

Heterogeneity of the Axon Initial Segment in Interneurons and Pyramidal Cells of Rodent Visual Cortex

PubMed Central

Höfflin, Felix; Jack, Alexander; Riedel, Christian; Mack-Bucher, Julia; Roos, Johannes; Corcelli, Corinna; Schultz, Christian; Wahle, Petra; Engelhardt, Maren

2017-01-01

The microdomain that orchestrates action potential initiation in neurons is the axon initial segment (AIS). It has long been considered to be a rather homogeneous domain at the very proximal axon hillock with relatively stable length, particularly in cortical pyramidal cells. However, studies in other brain regions paint a different picture. In hippocampal CA1, up to 50% of axons emerge from basal dendrites. Further, in about 30% of thick-tufted layer V pyramidal neurons in rat somatosensory cortex, axons have a dendritic origin. Consequently, the AIS is separated from the soma. Recent in vitro and in vivo studies have shown that cellular excitability is a function of AIS length/position and somatodendritic morphology, undermining a potentially significant impact of AIS heterogeneity for neuronal function. We therefore investigated neocortical axon morphology and AIS composition, hypothesizing that the initial observation of seemingly homogeneous AIS is inadequate and needs to take into account neuronal cell types. Here, we biolistically transfected cortical neurons in organotypic cultures to visualize the entire neuron and classify cell types in combination with immunolabeling against AIS markers. Using confocal microscopy and morphometric analysis, we investigated axon origin, AIS position, length, diameter as well as distance to the soma. We find a substantial AIS heterogeneity in visual cortical neurons, classified into three groups: (I) axons with somatic origin with proximal AIS at the axon hillock; (II) axons with somatic origin with distal AIS, with a discernible gap between the AIS and the soma; and (III) axons with dendritic origin (axon-carrying dendrite cell, AcD cell) and an AIS either starting directly at the axon origin or more distal to that point. Pyramidal cells have significantly longer AIS than interneurons. Interneurons with vertical columnar axonal projections have significantly more distal AIS locations than all other cells with their prevailing phenotype as an AcD cell. In contrast, neurons with perisomatic terminations display most often an axon originating from the soma. Our data contribute to the emerging understanding that AIS morphology is highly variable, and potentially a function of the cell type. PMID:29170630

Quantum Effect Physics, Electronics and Applications: Proceedings of the International Workshop Held in Luxor, Egypt on January 6-10, 1992

DTIC Science & Technology

1992-12-15

Giza Engineering Systems, Fujitsu, Hitachi, Matsushita, Mitsubishi, NEC, BTT, Sanyo, Sony. and Toshiba. K lsmail T Ikoma H I Smith Organizing and...etch and the i"• development of low etch rate surfaces were used for the fabrication of pyramid - shaped ridges with the QWs forming buried layers...inside the pyramids . "a/s Depending on the etch-depth, the wire /\

Loss of MeCP2 From Forebrain Excitatory Neurons Leads to Cortical Hyperexcitation and Seizures

PubMed Central

Zhang, Wen; Peterson, Matthew; Beyer, Barbara; Frankel, Wayne N.

2014-01-01

Mutations of MECP2 cause Rett syndrome (RTT), a neurodevelopmental disorder leading to loss of motor and cognitive functions, impaired social interactions, and seizure at young ages. Defects of neuronal circuit development and function are thought to be responsible for the symptoms of RTT. The majority of RTT patients show recurrent seizures, indicating that neuronal hyperexcitation is a common feature of RTT. However, mechanisms underlying hyperexcitation in RTT are poorly understood. Here we show that deletion of Mecp2 from cortical excitatory neurons but not forebrain inhibitory neurons in the mouse leads to spontaneous seizures. Selective deletion of Mecp2 from excitatory but not inhibitory neurons in the forebrain reduces GABAergic transmission in layer 5 pyramidal neurons in the prefrontal and somatosensory cortices. Loss of MeCP2 from cortical excitatory neurons reduces the number of GABAergic synapses in the cortex, and enhances the excitability of layer 5 pyramidal neurons. Using single-cell deletion of Mecp2 in layer 2/3 pyramidal neurons, we show that GABAergic transmission is reduced in neurons without MeCP2, but is normal in neighboring neurons with MeCP2. Together, these results suggest that MeCP2 in cortical excitatory neurons plays a critical role in the regulation of GABAergic transmission and cortical excitability. PMID:24523563

Pyramidal cell-interneuron interactions underlie hippocampal ripple oscillations.

PubMed

Stark, Eran; Roux, Lisa; Eichler, Ronny; Senzai, Yuta; Royer, Sebastien; Buzsáki, György

2014-07-16

High-frequency ripple oscillations, observed most prominently in the hippocampal CA1 pyramidal layer, are associated with memory consolidation. The cellular and network mechanisms underlying the generation, frequency control, and spatial coherence of the rhythm are poorly understood. Using multisite optogenetic manipulations in freely behaving rodents, we found that depolarization of a small group of nearby pyramidal cells was sufficient to induce high-frequency oscillations, whereas closed-loop silencing of pyramidal cells or activation of parvalbumin- (PV) or somatostatin-immunoreactive interneurons aborted spontaneously occurring ripples. Focal pharmacological blockade of GABAA receptors abolished ripples. Localized PV interneuron activation paced ensemble spiking, and simultaneous induction of high-frequency oscillations at multiple locations resulted in a temporally coherent pattern mediated by phase-locked interneuron spiking. These results constrain competing models of ripple generation and indicate that temporally precise local interactions between excitatory and inhibitory neurons support ripple generation in the intact hippocampus. Copyright © 2014 Elsevier Inc. All rights reserved.

Pyramidal Cell-Interneuron Interactions Underlie Hippocampal Ripple Oscillations

PubMed Central

Stark, Eran; Roux, Lisa; Eichler, Ronny; Senzai, Yuta; Royer, Sebastien; Buzsáki, György

2015-01-01

SUMMARY High-frequency ripple oscillations, observed most prominently in the hippocampal CA1 pyramidal layer, are associated with memory consolidation. The cellular and network mechanisms underlying the generation, frequency control, and spatial coherence of the rhythm are poorly understood. Using multisite optogenetic manipulations in freely behaving rodents, we found that depolarization of a small group of nearby pyramidal cells was sufficient to induce high-frequency oscillations, whereas closed-loop silencing of pyramidal cells or activation of parvalbumin-(PV) or somatostatin-immunoreactive interneurons aborted spontaneously occurring ripples. Focal pharmacological blockade of GABAA receptors abolished ripples. Localized PV inter-neuron activation paced ensemble spiking, and simultaneous induction of high-frequency oscillations at multiple locations resulted in a temporally coherent pattern mediated by phase-locked inter-neuron spiking. These results constrain competing models of ripple generation and indicate that temporally precise local interactions between excitatory and inhibitory neurons support ripple generation in the intact hippocampus. PMID:25033186

Modulation of NMDA and AMPA-Mediated Synaptic Transmission by CB1 Receptors in Frontal Cortical Pyramidal Cells

PubMed Central

Li, Qiang; Yan, Haidun; Wilson, Wilkie A.; Swartzwelder, H. Scott

2010-01-01

Although the endogenous cannabinoid system modulates a variety of physiological and pharmacological processes, the specific role of cannabinoid CB1 receptors in the modulation of glutamatergic neurotransmission and neural plasticity is not well understood. Using whole-cell patch clamp recording techniques, evoked or spontaneous excitatory postsynaptic currents (eEPSCs or sEPSCs) were recorded from visualized, layer II/III pyramidal cells in frontal cortical slices from rat brain. Bath application of the CB1 receptor agonist, WIN 55212-2 (WIN), reduced the amplitude of NMDA receptor-mediated EPSCs in a concentration-dependent manner. When co-applied with the specific CB1 antagonists, AM251 or AM281, WIN did not suppress NMDA receptor mediated EPSCs. WIN also reduced the amplitude of evoked AMPA receptor-mediated EPSCs, an effect that was also reversed by AM251. Both the frequency and amplitude of spontaneous AMPA receptor-mediated EPSCs were significantly reduced by WIN. In contrast, WIN reduced the frequency, but not the amplitude of miniature EPSCs, suggesting that the suppression of glutmatergic activity by CB1 receptors in the frontal neocortex is mediated by a pre-synaptic mechanism. Taken together, these data indicate a critical role for endocannabinoid signaling in the regulation of excitatory synaptic transmission in frontal neocortex, and suggest a possible neuronal mechanism whereby THC regulates cortical function. PMID:20420813

Dopaminergic Modulation of Excitatory Transmission in the Anterior Cingulate Cortex of Adult Mice

PubMed Central

Darvish-Ghane, Soroush; Yamanaka, Manabu

2016-01-01

Dopamine (DA) possesses potent neuromodulatory properties in the central nervous system. In the anterior cingulate cortex, α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPAR) are key ion channels in mediating nerve injury induced long-term potentiation (LTP) and chronic pain phenotype. In the present study, we reported the effects of DA on glutamate mediated excitatory post-synaptic currents (EPSCs) in pyramidal neurons of layer II/III of the ACC in adult mice. Bath application of DA (50 μM) caused a significant, rapid and reversible inhibition of evoked EPSCs (eEPSC). This inhibitory effect is dose-related and was absent in lower concentration of DA (5 μM). Furthermore, selective postsynaptic application of GDP-β-S (1.6 mM) in the internal solution completely abolished the inhibitory effects of DA (50 μM). We also investigated modulation of spontaneous EPSCs (sEPSCs) and TTX sensitive, miniature EPSCs (mEPSCs) by DA. Our results indicated mixed effects of potentiation and inhibition of frequency and amplitude for sEPSCs and mEPSCs. Furthermore, high doses of SCH23390 (100 μM) and sulpiride (100 μM) revealed that, inhibition of eEPSCs is mediated by postsynaptic D2-receptors (D2R). Our finding posits a pre- and postsynaptic mode of pyramidal neuron EPSC modulation in mice ACC by DA. PMID:27317578

The role of charge transfer in the oxidation state change of Ce atoms in the TM13-CeO2(111) systems (TM = Pd, Ag, Pt, Au): a DFT + U investigation.

PubMed

Tereshchuk, Polina; Freire, Rafael L H; Ungureanu, Crina G; Seminovski, Yohanna; Kiejna, Adam; Da Silva, Juarez L F

2015-05-28

Despite extensive studies of transition metal (TM) clusters supported on ceria (CeO2), fundamental issues such as the role of the TM atoms in the change in the oxidation state of Ce atoms are still not well understood. In this work, we report a theoretical investigation based on static and ab initio molecular dynamics density functional theory calculations of the interaction of 13-atom TM clusters (TM = Pd, Ag, Pt, Au) with the unreduced CeO2(111) surface represented by a large surface unit cell and employing Hubbard corrections for the strong on-site Coulomb correlation in the Ce f-electrons. We found that the TM13 clusters form pyramidal-like structures on CeO2(111) in the lowest energy configurations with the following stacking sequence, TM/TM4/TM8/CeO2(111), while TM13 adopts two-dimensional structures at high energy structures. TM13 induces a change in the oxidation state of few Ce atoms (3 of 16) located in the topmost Ce layer from Ce(IV) (itinerant Ce f-states) to Ce(III) (localized Ce f-states). There is a charge flow from the TM atoms to the CeO2(111) surface, which can be explained by the electronegativity difference between the TM (Pd, Ag, Pt, Au) and O atoms, however, the charge is not uniformly distributed on the topmost O layer due to the pressure induced by the TM13 clusters on the underlying O ions, which yields a decrease in the ionic charge of the O ions located below the cluster and an increase in the remaining O ions. Due to the charge flow mainly from the TM8-layer to the topmost O-layer, the charge cannot flow from the Ce(IV) atoms to the O atoms with the same magnitude as in the clean CeO2(111) surface. Consequently, the effective cationic charge decreases mainly for the Ce atoms that have a bond with the O atoms not located below the cluster, and hence, those Ce atoms change their oxidation state from IV to III. This increases the size of the Ce(III) compared with the Ce(IV) cations, which builds-in a strain within the topmost Ce layer, and hence, also affecting the location of the Ce(III) cations and the structure of the TM13 clusters.

Temporal redistribution of inhibition over neuronal subcellular domains underlies state-dependent rhythmic change of excitability in the hippocampus

PubMed Central

Somogyi, Peter; Katona, Linda; Klausberger, Thomas; Lasztóczi, Bálint; Viney, Tim J.

2014-01-01

The behaviour-contingent rhythmic synchronization of neuronal activity is reported by local field potential oscillations in the theta, gamma and sharp wave-related ripple (SWR) frequency ranges. In the hippocampus, pyramidal cell assemblies representing temporal sequences are coordinated by GABAergic interneurons selectively innervating specific postsynaptic domains, and discharging phase locked to network oscillations. We compare the cellular network dynamics in the CA1 and CA3 areas recorded with or without anaesthesia. All parts of pyramidal cells, except the axon initial segment, receive GABA from multiple interneuron types, each with distinct firing dynamics. The axon initial segment is exclusively innervated by axo-axonic cells, preferentially firing after the peak of the pyramidal layer theta cycle, when pyramidal cells are least active. Axo-axonic cells are inhibited during SWRs, when many pyramidal cells fire synchronously. This dual inverse correlation demonstrates the key inhibitory role of axo-axonic cells. Parvalbumin-expressing basket cells fire phase locked to field gamma activity in both CA1 and CA3, and also strongly increase firing during SWRs, together with dendrite-innervating bistratified cells, phasing pyramidal cell discharge. Subcellular domain-specific GABAergic innervation probably developed for the coordination of multiple glutamatergic inputs on different parts of pyramidal cells through the temporally distinct activity of GABAergic interneurons, which differentially change their firing during different network states. PMID:24366131

Colloidal quantum dot solar cells exploiting hierarchical structuring.

PubMed

Labelle, André J; Thon, Susanna M; Masala, Silvia; Adachi, Michael M; Dong, Haopeng; Farahani, Maryam; Ip, Alexander H; Fratalocchi, Andrea; Sargent, Edward H

2015-02-11

Extremely thin-absorber solar cells offer low materials utilization and simplified manufacture but require improved means to enhance photon absorption in the active layer. Here, we report enhanced-absorption colloidal quantum dot (CQD) solar cells that feature transfer-stamped solution-processed pyramid-shaped electrodes employed in a hierarchically structured device. The pyramids increase, by up to a factor of 2, the external quantum efficiency of the device at absorption-limited wavelengths near the absorber band edge. We show that absorption enhancement can be optimized with increased pyramid angle with an appreciable net improvement in power conversion efficiency, that is, with the gain in current associated with improved absorption and extraction overcoming the smaller fractional decrease in open-circuit voltage associated with increased junction area. We show that the hierarchical combination of micron-scale structured electrodes with nanoscale films provides for an optimized enhancement at absorption-limited wavelengths. We fabricate 54.7° pyramid-patterned electrodes, conformally apply the quantum dot films, and report pyramid CQD solar cells that exhibit a 24% improvement in overall short-circuit current density with champion devices providing a power conversion efficiency of 9.2%.

Extraction of texture features with a multiresolution neural network

NASA Astrophysics Data System (ADS)

Lepage, Richard; Laurendeau, Denis; Gagnon, Roger A.

1992-09-01

Texture is an important surface characteristic. Many industrial materials such as wood, textile, or paper are best characterized by their texture. Detection of defaults occurring on such materials or classification for quality control anD matching can be carried out through careful texture analysis. A system for the classification of pieces of wood used in the furniture industry is proposed. This paper is concerned with a neural network implementation of the features extraction and classification components of the proposed system. Texture appears differently depending at which spatial scale it is observed. A complete description of a texture thus implies an analysis at several spatial scales. We propose a compact pyramidal representation of the input image for multiresolution analysis. The feature extraction system is implemented on a multilayer artificial neural network. Each level of the pyramid, which is a representation of the input image at a given spatial resolution scale, is mapped into a layer of the neural network. A full resolution texture image is input at the base of the pyramid and a representation of the texture image at multiple resolutions is generated by the feedforward pyramid structure of the neural network. The receptive field of each neuron at a given pyramid level is preprogrammed as a discrete Gaussian low-pass filter. Meaningful characteristics of the textured image must be extracted if a good resolving power of the classifier must be achieved. Local dominant orientation is the principal feature which is extracted from the textured image. Local edge orientation is computed with a Sobel mask at four orientation angles (multiple of (pi) /4). The resulting intrinsic image, that is, the local dominant orientation image, is fed to the texture classification neural network. The classification network is a three-layer feedforward back-propagation neural network.

Early Postnatal Lesion of the Medial Dorsal Nucleus Leads to Loss of Dendrites and Spines in Adult Prefrontal Cortex

PubMed Central

Marmolejo, Naydu; Paez, Jesse; Levitt, Jonathan B.; Jones, Liesl B.

2013-01-01

Research suggests that the medial dorsal nucleus (MD) of the thalamus influences pyramidal cell development in the prefrontal cortex (PFC) in an activity-dependent manner. The MD is reciprocally connected to the PFC. Many psychiatric disorders, such as schizophrenia, affect the PFC, and one of the most consistent findings in schizophrenia is a decrease in volume and neuronal number in the MD. Therefore, understanding the role the MD plays in the development of the PFC is important and may help in understanding the progression of psychiatric disorders that have their root in development. Focusing on the interplay between the MD and the PFC, this study examined the hypothesis that the MD plays a role in the dendritic development of pyramidal cells in the PFC. Unilateral electrolytic lesions of the MD in Long-Evans rat pups were made on postnatal day 4 (P4), and the animals developed to P60. We then examined dendritic morphology by examining MAP2 immunostaining and by using Golgi techniques to determine basilar dendrite number and spine density. Additionally, we examined pyramidal cell density in cingulate area 1 (Cg1), prelimbic region, and dorsolateral anterior cortex, which receive afferents from the MD. Thalamic lesions caused a mean MD volume decrease of 12.4% which led to a significant decrease in MAP2 staining in both superficial and deep layers in all 3 cortical areas. The lesions also caused a significant decrease in spine density and in the number of primary and secondary basilar dendrites on superficial and deep layer pyramidal neurons in all 3 regions. No significant difference was observed in pyramidal cell density in any of the regions or layers, but a nonsignificant increase in cell density was observed in 2 regions. Our data are thus consistent with the hypothesis that the MD plays a role in the development of the PFC and, therefore, may be a good model to begin to examine neurodevelopmental disorders such as autism and schizophrenia. PMID:23406908

A π-π 3D network of tetranuclear μ2/μ3-carbonato Dy(III) bis-pyrazolylpyridine clusters showing single molecule magnetism features.

PubMed

Gass, Ian A; Moubaraki, Boujemaa; Langley, Stuart K; Batten, Stuart R; Murray, Keith S

2012-02-18

2,6-Di(pyrazole-3-yl)pyridine, 3-bpp, forms a porous (4(9)·6(6)) π-π mediated 3D network of trigonal pyramidal [Dy(III)(4)] carbonato-bridged complexes, with hexagonal channels comprising 54% of the unit cell volume, the material displaying slow magnetisation reversal. This journal is © The Royal Society of Chemistry 2012

Does the visual system of the flying fox resemble that of primates? The distribution of calcium-binding proteins in the primary visual pathway of Pteropus poliocephalus.

PubMed

Ichida, J M; Rosa, M G; Casagrande, V A

2000-01-31

It has been proposed that flying foxes and echolocating bats evolved independently from early mammalian ancestors in such a way that flying foxes form one of the suborders most closely related to primates. A major piece of evidence offered in support of a flying fox-primate link is the highly developed visual system of flying foxes, which is theorized to be primate-like in several different ways. Because the calcium-binding proteins parvalbumin (PV) and calbindin (CB) show distinct and consistent distributions in the primate visual system, the distribution of these same proteins was examined in the flying fox (Pteropus poliocephalus) visual system. Standard immunocytochemical techniques reveal that PV labeling within the lateral geniculate nucleus (LGN) of the flying fox is sparse, with clearly labeled cells located only within layer 1, adjacent to the optic tract. CB labeling in the LGN is profuse, with cells labeled in all layers throughout the nucleus. Double labeling reveals that all PV+ cells also contain CB, and that these cells are among the largest in the LGN. In primary visual cortex (V1) PV and CB label different classes of non-pyramidal neurons. PV+ cells are found in all cortical layers, although labeled cells are found only rarely in layer I. CB+ cells are found primarily in layers II and III. The density of PV+ neuropil correlates with the density of cytochrome oxidase staining; however, no CO+ or PV+ or CB+ patches or blobs are found in V1. These results show that the distribution of calcium-binding proteins in the flying fox LGN is unlike that found in primates, in which antibodies for PV and CB label specific separate populations of relay cells that exist in different layers. Indeed, the pattern of calcium-binding protein distribution in the flying fox LGN is different from that reported in any other terrestrial mammal. Within V1 no PV+ patches, CO blobs, or patchy distribution of CB+ neuropil that might reveal interblobs characteristic of primate V1 are found; however, PV and CB are found in separate populations of non-pyramidal neurons. The types of V1 cells labeled with antibodies to PV and CB in all mammals examined including the flying fox suggest that the similarities in the cellular distribution of these proteins in cortex reflect the fact that this feature is common to all mammals.

Pyramidal tract stimulation restores normal corticospinal tract connections and visuomotor skill after early postnatal motor cortex activity blockade

PubMed Central

Salimi, I; Friel, KM; Martin, JH

2008-01-01

Motor development depends on forming specific connections between the corticospinal tract (CST) and the spinal cord. Blocking CST activity in kittens during the critical period for establishing connections with spinal motor circuits results in permanent impairments in connectivity and function. The changes in connections are consistent with the hypothesis that the inactive tract is less competitive in developing spinal connections than the active tract. In this study we tested the competition hypothesis by determining if activating CST axons, after prior silencing during the critical period, abrogated development of aberrant corticospinal connections and motor impairments. In kittens, we inactivated motor cortex by muscimol infusion between postnatal weeks 5-7. We next electrically stimulated CST axons in the medullary pyramid 2.5 hours daily, between weeks 7-10. In controls (n=3), CST terminations were densest within the contralateral deeper, premotor, spinal layers. After prior inactivation (n=3), CST terminations were densest within the dorsal, somatic sensory, layers. There were more ipsilateral terminations from the active tract. During visually guided locomotion, there was a movement endpoint impairment. Stimulation after inactivation (n=6) resulted in significantly fewer terminations in the sensory layers and more in the premotor layers, and fewer ipsilateral connections from active cortex. Chronic stimulation reduced the current threshold for evoking contralateral movements by pyramidal stimulation, suggesting strengthening of connections. Importantly, stimulation significantly improved stepping accuracy. These findings show the importance of activity-dependent processes in specifying CST connections. They also provide a strategy for harnessing activity to rescue CST axons at risk of developing aberrant connections after CNS injury. PMID:18632946

Neuropathic Pain Causes Pyramidal Neuronal Hyperactivity in the Anterior Cingulate Cortex.

PubMed

Zhao, Ruohe; Zhou, Hang; Huang, Lianyan; Xie, Zhongcong; Wang, Jing; Gan, Wen-Biao; Yang, Guang

2018-01-01

The anterior cingulate cortex (ACC) is thought to be important for acute pain perception as well as the development of chronic pain after peripheral nerve injury. Nevertheless, how ACC neurons respond to sensory stimulation under chronic pain states is not well understood. Here, we used an in vivo two-photon imaging technique to monitor the activity of individual neurons in the ACC of awake, head restrained mice. Calcium imaging in the dorsal ACC revealed robust somatic activity in layer 5 (L5) pyramidal neurons in response to peripheral noxious stimuli, and the degree of evoked activity was correlated with the intensity of noxious stimulation. Furthermore, the activation of ACC neurons occurred bilaterally upon noxious stimulation to either contralateral or ipsilateral hind paws. Notably, with nerve injury-induced neuropathic pain in one limb, L5 pyramidal neurons in both sides of the ACC showed enhanced activity in the absence or presence of pain stimuli. These results reveal hyperactivity of L5 pyramidal neurons in the bilateral ACC during the development of neuropathic pain.

Effect of Noopept on Dynamics of Intracellular Calcium in Neurons of Cultured Rat Hippocampal Slices.

PubMed

Kolbaev, S N; Aleksandrova, O P; Sharonova, I N; Skrebitsky, V G

2018-01-01

A neuroprotective and nootropic drug Noopept increased the frequency of spontaneous calcium transients in neurons of CA1 radial layer in cultured rat hippocampal slices. In contrast, the drug exerted no significant effect on intracellular calcium concentration and its dynamics in neurons of hippocampal CA1 pyramidal layer.

Selective alterations of neurons and circuits related to early memory loss in Alzheimer’s disease

PubMed Central

Llorens-Martín, Maria; Blazquez-Llorca, Lidia; Benavides-Piccione, Ruth; Rabano, Alberto; Hernandez, Felix; Avila, Jesus; DeFelipe, Javier

2014-01-01

A progressive loss of episodic memory is a well-known clinical symptom that characterizes Alzheimer’s disease (AD). The beginning of this loss of memory has been associated with the very early, pathological accumulation of tau and neuronal degeneration observed in the entorhinal cortex (EC). Tau-related pathology is thought to then spread progressively to the hippocampal formation and other brain areas as the disease progresses. The major cortical afferent source of the hippocampus and dentate gyrus is the EC through the perforant pathway. At least two main circuits participate in the connection between EC and the hippocampus; one originating in layer II and the other in layer III of the EC giving rise to the classical trisynaptic (ECII → dentate gyrus → CA3 → CA1) and monosynaptic (ECIII → CA1) circuits. Thus, the study of the early pathological changes in these circuits is of great interest. In this review, we will discuss mainly the alterations of the granule cell neurons of the dentate gyrus and the atrophy of CA1 pyramidal neurons that occur in AD in relation to the possible differential alterations of these two main circuits. PMID:24904307

Selective alterations of neurons and circuits related to early memory loss in Alzheimer's disease.

PubMed

Llorens-Martín, Maria; Blazquez-Llorca, Lidia; Benavides-Piccione, Ruth; Rabano, Alberto; Hernandez, Felix; Avila, Jesus; DeFelipe, Javier

2014-01-01

A progressive loss of episodic memory is a well-known clinical symptom that characterizes Alzheimer's disease (AD). The beginning of this loss of memory has been associated with the very early, pathological accumulation of tau and neuronal degeneration observed in the entorhinal cortex (EC). Tau-related pathology is thought to then spread progressively to the hippocampal formation and other brain areas as the disease progresses. The major cortical afferent source of the hippocampus and dentate gyrus is the EC through the perforant pathway. At least two main circuits participate in the connection between EC and the hippocampus; one originating in layer II and the other in layer III of the EC giving rise to the classical trisynaptic (ECII → dentate gyrus → CA3 → CA1) and monosynaptic (ECIII → CA1) circuits. Thus, the study of the early pathological changes in these circuits is of great interest. In this review, we will discuss mainly the alterations of the granule cell neurons of the dentate gyrus and the atrophy of CA1 pyramidal neurons that occur in AD in relation to the possible differential alterations of these two main circuits.

"Brief report: increase in production of spoken words in some children with autism after PECS teaching to Phase III".

PubMed

Carr, Deborah; Felce, Janet

2007-04-01

The context for this work was an evaluation study [Carr, D., & Felce, J. A. (in press)] of the early phases of the Picture Exchange Communication System (PECS) [Frost, L. A., & Bondy, A. S. (1994). The picture exchange communication system training manual. Cherry Hill, NJ: Pyramid Educational Consultants, Inc.; Frost, L. A., & Bondy, A. S. (2004). The picture exchange communication system training manual, 2nd edn. Newark, DE: Pyramid Educational Consultants, Inc.]. This paper reports that five of 24 children who received 15 h of PECS teaching towards Phase III over a period of 4-5 weeks, showed concomitant increases in speech production, either in initiating communication with staff or in responding, or both. No children in the PECS group demonstrated a decrease in spoken words after receiving PECS teaching. In the control group, only one of 17 children demonstrated a minimal increase and four of 17 children demonstrated a decrease in use of spoken words after a similar period without PECS teaching.

Intracerebroventricular administration of growth hormone induces morphological changes in pyramidal neurons of the hippocampus and prefrontal cortex in adult rats.

PubMed

Olivares-Hernández, Juan David; García-García, Fabio; Camacho-Abrego, Israel; Flores, Gonzalo; Juárez-Aguilar, Enrique

2018-07-01

A growing body of evidence suggests that growth hormone (GH) affects synaptic plasticity at both the molecular and electrophysiological levels. However, unclear is whether plasticity that is stimulated by GH is associated with changes in neuron structure. This study investigated the effect of intracerebroventricular (ICV) administration of GH on the morphology of pyramidal neurons of the CA1 region of the dorsal hippocampus and layer III of the prefrontal cortex. Male Wistar rats received daily ICV injections of GH (120 ng) for 7 days, and they were euthanized 21 days later. Changes in neuronal morphology were evaluated using Golgi-Cox staining and subsequent Sholl analysis. GH administration increased total dendritic length in the CA1 region of the dorsal hippocampus and prefrontal cortex. The Sholl analysis revealed an increase in dendritic length of the third to eighth branch orders in the hippocampus and from the third to sixth branch orders in the prefrontal cortex. Interestingly, GH treatment increased the density of dendritic spines in both brain regions, favoring the presence of mushroom-like spines only in the CA1 hippocampal region. Our results indicated that GH induces changes in the length of dendritic trees and the density of dendritic spines in two high-plasticity brain regions, suggesting that GH-induced synaptic plasticity at the molecular and electrophysiological levels may be associated with these structural changes in neurons. © 2018 Wiley Periodicals, Inc.

SSMILes: School Science and Mathematics Integrated Lessons: Chocolate Chip Cookies: A Consumer Unit, Part III: Investigating Snacks.

ERIC Educational Resources Information Center

Pearlman, Susan; Pericak-Spector, Kathleen

1995-01-01

Gives lesson plans for activities integrating mathematics and science in which students collect data on the nutritional makeup of a number of snack foods and relate this information to the recommendations of the food guide pyramid. (MKR)

GABAA receptor-mediated currents in interneurons and pyramidal cells of rat visual cortex

PubMed Central

Xiang, Zixiu; Huguenard, John R; Prince, David A

1998-01-01

We compared γ-aminobutyric acid (GABA)-mediated responses of identified pyramidal cells and fast spiking interneurons in layer V of visual cortical slices from young rats (P11-14). The frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) was similar in pyramidal cells and interneurons (1.7 vs. 1.9 Hz). For events with 10-90 % rise times less than 0.9 ms, no significant differences were found in mean amplitude (61 vs. 65 pA), mean rise time (0.58 vs. 0.61 ms), or the first time constant of decay (τ1, 6.4 vs. 6.5 ms) between pyramidal cells and interneurons. The second decay time constant (τ2) was significantly longer in interneurons than in pyramidal cells (49 vs. 22 ms). The difference in sIPSC decay kinetics between two cell types also existed in adult rats (P36-42), suggesting the kinetic difference is not due to differential development of GABAA receptors in these cell types. The decay kinetics of monosynaptic evoked IPSCs were also longer in interneurons. As in the case of sIPSCs, the difference was accounted for by the second decay time constant. τ1 and τ2 were, respectively, 13 and 64 ms for interneurons and 12 and 47 ms for pyramidal cells. Cell-attached patch recordings revealed that the mean open time for single Cl− channels in response to 2 μM GABA was significantly longer in interneurons than pyramidal cells (5.0 vs. 2.8 ms). The chord conductance of these channels in interneurons (12 pS) was significantly smaller than in pyramidal cells (15 pS). Single channel currents reversed polarity when the pipette potential was approximately -10 mV for both cell types. These results show that there is a functional diversity of GABAA receptors in electrophysiologically and morphologically identified cortical pyramidal cells and interneurons. This diversity might derive from the different molecular composition of the receptors in these two cell types. PMID:9503333

Efficient light harvesting with micropatterned 3D pyramidal photoanodes in dye-sensitized solar cells.

PubMed

Wooh, Sanghyuk; Yoon, Hyunsik; Jung, Jae-Hyun; Lee, Yong-Gun; Koh, Jai Hyun; Lee, Byoungho; Kang, Yong Soo; Char, Kookheon

2013-06-11

3D TiO2 photoanodes in dye-sensitized solar cells (DSCs) are fabricated by the soft lithographic technique for efficient light trapping. An extended strategy to the construction of randomized pyramid structure is developed by the conventional wet-etching of a silicon wafer for low-cost fabrication. Moreover, the futher enhancement of light absorption resulting in photocurrent increase is achieved by combining the 3D photoanode with a conventional scattering layer. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zimmermann, Iwan; Kremer, Reinhard K.; Johnsson, Mats, E-mail: mats.johnsson@mmk.su.se

The new compounds Mn{sub 4}(TeO{sub 3})(SiO{sub 4})X{sub 2} (X=Br, Cl) were synthesized by solid state reactions in sealed evacuated silica tubes. The compounds crystallize in the monoclinic space group P2{sub 1}/m with the unit cell parameters a=5.5463(3) Å (5.49434(7) Å), b=6.4893(4) Å (6.44184(9) Å), c=12.8709(7) Å (12.60451(18) Å), β=93.559(5)° (94.1590(12)°) and Z=2 for the respective Br and Cl analogues. Manganese adopts various distorted coordination polyhedra; [MnO{sub 6}] octahedra, [MnO{sub 5}] tetragonal pyramids and [MnO{sub 2}X{sub 2}] tetrahedra. Other building blocks are [SiO{sub 4}] tetrahedra and [TeO{sub 3}] trigonal pyramids. The structure is made up from layers having no net chargemore » that are connected via weak Van der Waal interactions. The layers that are parallel to (1 1 0) consist of two manganese oxide sheets which are separated by [SiO{sub 4}] tetrahedra. On the outer sides of the sheets are the [MnO{sub 2}X{sub 2}] tetrahedra and the [TeO{sub 3}] trigonal pyramids connected so that the halide ions and the stereochemically active lone pairs on the tellurium atoms protrude from the layers. Magnetic susceptibility measurements reveal a Curie law with a Weiss temperature of θ=−153(3) K for temperatures ≥100 K and indicate antiferromagnetic ordering at T{sub N} ∼4 K. Possible structural origins of the large frustration parameter of f=38 are discussed. - Graphical abstract: Table of contents caption. The new compounds Mn{sub 4}(TeO{sub 3})(SiO{sub 4})X{sub 2} (X=Br, Cl) are layered with weak Van der Waal interactions in between the layers. Manganese adopts various distorted coordination polyhedral, other building blocks are [SiO{sub 4}] tetrahedra and [TeO{sub 3}] trigonal pyramids. Magnetic susceptibility measurements indicate antiferromagnetic ordering at low temperatures and a large frustration parameter. - Highlights: • Two new isostructural oxohalide compounds are described. • The compounds are the first examples of oxohalides containing both Te{sup 4+} and Si{sup 4+}. • Both compounds display the unusual coordination polyhedron MnO{sub 2}X{sub 2} (X=Cl, Br). • The compounds are made up of charge neutral layers connected via weak interactions. • The compounds are antiferromagnetic and display a large frustration parameter.« less

Social Isolation During the Critical Period Reduces Synaptic and Intrinsic Excitability of a Subtype of Pyramidal Cell in Mouse Prefrontal Cortex.

PubMed

Yamamuro, Kazuhiko; Yoshino, Hiroki; Ogawa, Yoichi; Makinodan, Manabu; Toritsuka, Michihiro; Yamashita, Masayuki; Corfas, Gabriel; Kishimoto, Toshifumi

2018-03-01

Juvenile social experience is crucial for the functional development of forebrain regions, especially the prefrontal cortex (PFC). We previously reported that social isolation for 2 weeks after weaning induces prefrontal cortex dysfunction and hypomyelination. However, the effect of social isolation on physiological properties of PFC neuronal circuit remained unknown. Since hypomyelination due to isolation is prominent in deep-layer of medial PFC (mPFC), we focused on 2 types of Layer-5 pyramidal cells in the mPFC: prominent h-current (PH) cells and nonprominent h-current (non-PH) cells. We found that a 2-week social isolation after weaning leads to a specific deterioration in action potential properties and reduction in excitatory synaptic inputs in PH cells. The effects of social isolation on PH cells, which involve reduction in functional glutamatergic synapses and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/N-methyl-d-aspartate charge ratio, are specific to the 2 weeks after weaning and to the mPFC. We conclude that juvenile social experience plays crucial roles in the functional development in a subtype of Layer-5 pyramidal cells in the mPFC. Since these neurons project to subcortical structures, a deficit in social experience during the critical period may result in immature neural circuitry between mPFC and subcortical targets. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Differences in the refractory properties of two distinct inhibitory circuitries in field CA1 of the hippocampus.

PubMed

Arai, A; Silberg, J; Lynch, G

1995-12-18

Extracellular reflections of IPSPs were examined in two distinct circuitries in field CA1 of the hippocampus. Stimulation in the stratum radiatum in the presence of AMPA receptor antagonists elicited positive potentials in the same stratum that were eliminated by picrotoxin, a blocker of GABAA receptors. Laminar profile analysis revealed that the response was maximal in the stratum radiatum at a point well distal to the pyramidal cell body layer and had a negative reflection in the stratum oriens. These field IPSPs presumably mediate the feedforward inhibition normally activated by the Schaffer-commissural projections to field CA1. Stimulation of the alveus produced an antidromic response followed by a much slower positive potential in recordings collected in the pyramidal cell layer. The latter response was suppressed by AMPA receptor antagonists or picrotoxin, as expected for disynaptic, recurrent (feedback) inhibition. The laminar profile for the feedback field IPSPs had its maximum near the pyramidal cell layer and its negative dipole in the stratum radiatum. Feedforward IPSPs were inhibited by about 50% if they were preceded within 200 ms by a priming pulse while feedback IPSPs were reduced by less than 20% under comparable conditions. The refractory effect was minimally dependent on stimulation intensity but was strongly affected by an antagonist of GABAB receptors. Attempts to modify IPSPs in the s. radiatum with long trains of low frequency stimulation or with theta-burst stimulation were not successful, suggesting that GABAergic synapses do not have the plasticities found in their glutamatergic counterparts. These results indicate that interneurons contacted by the extrinsic afferents of hippocampus form GABAergic synapses that differ in terms of spatial location and functional properties from the synapses generated by interneurons innervated by the recurrent collaterals of the pyramidal cells. The findings also suggest that repetitive afferent activity, while reducing the influence of dendritic IPSPs on excitatory input, will leave feedback suppression of cell spiking largely intact.

Mechanisms and consequences of action potential burst firing in rat neocortical pyramidal neurons

PubMed Central

Williams, Stephen R; Stuart, Greg J

1999-01-01

Electrophysiological recordings and pharmacological manipulations were used to investigate the mechanisms underlying the generation of action potential burst firing and its postsynaptic consequences in visually identified rat layer 5 pyramidal neurons in vitro.Based upon repetitive firing properties and subthreshold membrane characteristics, layer 5 pyramidal neurons were separated into three classes: regular firing and weak and strong intrinsically burst firing.High frequency (330 ± 10 Hz) action potential burst firing was abolished or greatly weakened by the removal of Ca2+ (n = 5) from, or by the addition of the Ca2+ channel antagonist Ni2+ (250–500 μm; n = 8) to, the perfusion medium.The blockade of apical dendritic sodium channels by the local dendritic application of TTX (100 nm; n = 5) abolished or greatly weakened action potential burst firing, as did the local apical dendritic application of Ni2+ (1 mm; n = 5).Apical dendritic depolarisation resulted in low frequency (157 ± 26 Hz; n = 6) action potential burst firing in regular firing neurons, as classified by somatic current injection. The intensity of action potential burst discharges in intrinsically burst firing neurons was facilitated by dendritic depolarisation (n = 11).Action potential amplitude decreased throughout a burst when recorded somatically, suggesting that later action potentials may fail to propagate axonally. Axonal recordings demonstrated that each action potential in a burst is axonally initiated and that no decrement in action potential amplitude is apparent in the axon > 30 μm from the soma.Paired recordings (n = 16) from synaptically coupled neurons indicated that each action potential in a burst could cause transmitter release. EPSPs or EPSCs evoked by a presynaptic burst of action potentials showed use-dependent synaptic depression.A postsynaptic, TTX-sensitive voltage-dependent amplification process ensured that later EPSPs in a burst were amplified when generated from membrane potentials positive to -60 mV, providing a postsynaptic mechanism that counteracts use-dependent depression at synapses between layer 5 pyramidal neurons. PMID:10581316

Synaptically activated Ca2+ waves in layer 2/3 and layer 5 rat neocortical pyramidal neurons

PubMed Central

Larkum, Matthew E; Watanabe, Shigeo; Nakamura, Takeshi; Lasser-Ross, Nechama; Ross, William N

2003-01-01

Calcium waves in layer 2/3 and layer 5 neocortical somatosensory pyramidal neurons were examined in slices from 2- to 8-week-old rats. Repetitive synaptic stimulation evoked a delayed, all-or-none [Ca2+]i increase primarily on the main dendritic shaft. This component was blocked by 1 mm (R,S)-α-methyl-4-carboxyphenylglycine (MCPG), 10 μm ryanodine, 1 mg ml−1 internal heparin, and was not blocked by 400 μm internal Ruthenium Red, indicating that it was due to Ca2+ release from internal stores by inositol 1,4,5-trisphosphate (IP3) mobilized via activation of metabotropic glutamate receptors. Calcium waves were initiated on the apical shaft at sites between the soma to around the main branch point, mostly at insertion points of oblique dendrites, and spread in both directions along the shaft. In the proximal dendrites the peak amplitude of the resulting [Ca2+]i change was much larger than that evoked by a train of Na+ spikes. In distal dendrites the peak amplitude was comparable to the [Ca2+]i change due to a Ca2+ spike. IP3-mediated Ca2+ release also was observed in the presence of the metabotropic agonists t-ACPD and carbachol when backpropagating spikes were generated. Ca2+ entry through NMDA receptors was observed primarily on the oblique dendrites. The main differences between waves in neocortical neurons and in previously described hippocampal pyramidal neurons were, (a) Ca2+ waves in L5 neurons could be evoked further out along the main shaft, (b) Ca2+ waves extended slightly further out into the oblique dendrites and (c) higher concentrations of bath-applied t-ACPD and carbachol were required to generate Ca2+ release events by backpropagating action potentials. PMID:12692172

A quantitative analysis of the local connectivity between pyramidal neurons in layers 2/3 of the rat visual cortex.

PubMed

Hellwig, B

2000-02-01

This study provides a detailed quantitative estimate for local synaptic connectivity between neocortical pyramidal neurons. A new way of obtaining such an estimate is presented. In acute slices of the rat visual cortex, four layer 2 and four layer 3 pyramidal neurons were intracellularly injected with biocytin. Axonal and dendritic arborizations were three-dimensionally reconstructed with the aid of a computer-based camera lucida system. In a computer experiment, pairs of pre- and postsynaptic neurons were formed and potential synaptic contacts were calculated. For each pair, the calculations were carried out for a whole range of distances (0 to 500 microm) between the presynaptic and the postsynaptic neuron, in order to estimate cortical connectivity as a function of the spatial separation of neurons. It was also differentiated whether neurons were situated in the same or in different cortical layers. The data thus obtained was used to compute connection probabilities, the average number of contacts between neurons, the frequency of specific numbers of contacts and the total number of contacts a dendritic tree receives from the surrounding cortical volume. Connection probabilities ranged from 50% to 80% for directly adjacent neurons and from 0% to 15% for neurons 500 microm apart. In many cases, connections were mediated by one contact only. However, close neighbors made on average up to 3 contacts with each other. The question as to whether the method employed in this study yields a realistic estimate of synaptic connectivity is discussed. It is argued that the results can be used as a detailed blueprint for building artificial neural networks with a cortex-like architecture.

Neurons and terminals in the retrohippocampal region in the rat's brain identified by anti-gamma-aminobutyric acid and anti-glutamic acid decarboxylase immunocytochemistry.

PubMed

Köhler, C; Wu, J Y; Chan-Palay, V

1985-01-01

The distribution of gamma-aminobutyric acid (GABA) containing nerve cells and terminals was studied at the light and electron microscopic levels in the retrohippocampal region of the rat by using anti-glutamic acid decarboxylase (GAD) and anti-GABA antibodies in immunocytochemistry. Large numbers of GAD and GABA stained cells were found in all retrohippocampal structures. At the ultrastructural level, the immunoreactivity against GABA and against the synthesizing enzyme GAD was localized to cytoplasmic structures, including loose clumps of rough endoplasmic reticulum, ribosomal arrays, outer mitochondrial surfaces and in axonal boutons. The GAD- and GABA-immunoreactive(-i) cells were found in all subfields of the retrohippocampal region (e.g., the subicular complex, the entorhinal area). Within the entorhinal area a slightly larger number of immunoreactive cells could be detected in layers II and III than in the other layers. In the subiculum, pre- and parasubiculum the GAD and GABA-i cells were present in relatively large numbers in all layers, except the molecular layer, which contained only a small number of GABA cells. Within the entorhinal area, GAD and GABA stained cells ranged in size from small (13 micron in diameter) to large (22 micron in diameter). A large number of different morphological classes of cells were found, except pyramidal and stellate cells. In the pre- and parasubiculum, on the other hand, the GABA cells were generally small to medium in size and morphologically more homogeneous than in the subiculum and entorhinal area. The entire retrohippocampal region was densely innervated by GABA preterminal processes, with little variation in the regional density of innervation. Within the entorhinal area, presubiculum and subiculum, a clear difference was found in the laminar pattern of innervation. In all three subfields the densest innervation was in layer II. In the entorhinal area both GAD- and GABA-i axons form palisades of fibers around the somata of neurons, which are tightly packed together in this layer. In the electron microscope both GAD-i and GABA-i were demonstrated in these axons. Axosomatic synaptic contacts were common between axons and the stellate neurons and other cells of this layer. Layers IV and VI appeared less dense in GAD-i terminals but appeared more densely innervated than layers III and V. The lamina dessicans was relatively poor in GAD-i. In the subiculum and presubiculum, as well as all other subfields of the hippocampal region, the innervation is dominated by axo-somatic innervation of layer II cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Ferromagnetic dinuclear mixed-valence Mn(II)/Mn(III) complexes: building blocks for the higher nuclearity complexes. structure, magnetic properties, and density functional theory calculations.

PubMed

Hänninen, Mikko M; Välivaara, Juha; Mota, Antonio J; Colacio, Enrique; Lloret, Francesc; Sillanpää, Reijo

2013-02-18

A series of six mixed-valence Mn(II)/Mn(III) dinuclear complexes were synthesized and characterized by X-ray diffraction. The reactivity of the complexes was surveyed, and structures of three additional trinuclear mixed-valence Mn(III)/Mn(II)/Mn(III) species were resolved. The magnetic properties of the complexes were studied in detail both experimentally and theoretically. All dinuclear complexes show ferromagnetic intramolecular interactions, which were justified on the basis of the electronic structures of the Mn(II) and Mn(III) ions. The large Mn(II)-O-Mn(III) bond angle and small distortion of the Mn(II) cation from the ideal square pyramidal geometry were shown to enhance the ferromagnetic interactions since these geometrical conditions seem to favor the orthogonal arrangement of the magnetic orbitals.

Transient increase in Zn2+ in hippocampal CA1 pyramidal neurons causes reversible memory deficit.

PubMed

Takeda, Atsushi; Takada, Shunsuke; Nakamura, Masatoshi; Suzuki, Miki; Tamano, Haruna; Ando, Masaki; Oku, Naoto

2011-01-01

The translocation of synaptic Zn(2+) to the cytosolic compartment has been studied to understand Zn(2+) neurotoxicity in neurological diseases. However, it is unknown whether the moderate increase in Zn(2+) in the cytosolic compartment affects memory processing in the hippocampus. In the present study, the moderate increase in cytosolic Zn(2+) in the hippocampus was induced with clioquinol (CQ), a zinc ionophore. Zn(2+) delivery by Zn-CQ transiently attenuated CA1 long-term potentiation (LTP) in hippocampal slices prepared 2 h after i.p. injection of Zn-CQ into rats, when intracellular Zn(2+) levels was transiently increased in the CA1 pyramidal cell layer, followed by object recognition memory deficit. Object recognition memory was transiently impaired 30 min after injection of ZnCl(2) into the CA1, but not after injection into the dentate gyrus that did not significantly increase intracellular Zn(2+) in the granule cell layer of the dentate gyrus. Object recognition memory deficit may be linked to the preferential increase in Zn(2+) and/or the preferential vulnerability to Zn(2+) in CA1 pyramidal neurons. In the case of the cytosolic increase in endogenous Zn(2+) in the CA1 induced by 100 mM KCl, furthermore, object recognition memory was also transiently impaired, while ameliorated by co-injection of CaEDTA to block the increase in cytosolic Zn(2+). The present study indicates that the transient increase in cytosolic Zn(2+) in CA1 pyramidal neurons reversibly impairs object recognition memory.

Transient Increase in Zn2+ in Hippocampal CA1 Pyramidal Neurons Causes Reversible Memory Deficit

PubMed Central

Takeda, Atsushi; Takada, Shunsuke; Nakamura, Masatoshi; Suzuki, Miki; Tamano, Haruna; Ando, Masaki; Oku, Naoto

2011-01-01

The translocation of synaptic Zn2+ to the cytosolic compartment has been studied to understand Zn2+ neurotoxicity in neurological diseases. However, it is unknown whether the moderate increase in Zn2+ in the cytosolic compartment affects memory processing in the hippocampus. In the present study, the moderate increase in cytosolic Zn2+ in the hippocampus was induced with clioquinol (CQ), a zinc ionophore. Zn2+ delivery by Zn-CQ transiently attenuated CA1 long-term potentiation (LTP) in hippocampal slices prepared 2 h after i.p. injection of Zn-CQ into rats, when intracellular Zn2+ levels was transiently increased in the CA1 pyramidal cell layer, followed by object recognition memory deficit. Object recognition memory was transiently impaired 30 min after injection of ZnCl2 into the CA1, but not after injection into the dentate gyrus that did not significantly increase intracellular Zn2+ in the granule cell layer of the dentate gyrus. Object recognition memory deficit may be linked to the preferential increase in Zn2+ and/or the preferential vulnerability to Zn2+ in CA1 pyramidal neurons. In the case of the cytosolic increase in endogenous Zn2+ in the CA1 induced by 100 mM KCl, furthermore, object recognition memory was also transiently impaired, while ameliorated by co-injection of CaEDTA to block the increase in cytosolic Zn2+. The present study indicates that the transient increase in cytosolic Zn2+ in CA1 pyramidal neurons reversibly impairs object recognition memory. PMID:22163318

Research on HDR image fusion algorithm based on Laplace pyramid weight transform with extreme low-light CMOS

NASA Astrophysics Data System (ADS)

Guan, Wen; Li, Li; Jin, Weiqi; Qiu, Su; Zou, Yan

2015-10-01

Extreme-Low-Light CMOS has been widely applied in the field of night-vision as a new type of solid image sensor. But if the illumination in the scene has drastic changes or the illumination is too strong, Extreme-Low-Light CMOS can't both clearly present the high-light scene and low-light region. According to the partial saturation problem in the field of night-vision, a HDR image fusion algorithm based on the Laplace Pyramid was researched. The overall gray value and the contrast of the low light image is very low. We choose the fusion strategy based on regional average gradient for the top layer of the long exposure image and short exposure image, which has rich brightness and textural features. The remained layers which represent the edge feature information of the target are based on the fusion strategy based on regional energy. In the process of source image reconstruction with Laplacian pyramid image, we compare the fusion results with four kinds of basal images. The algorithm is tested using Matlab and compared with the different fusion strategies. We use information entropy, average gradient and standard deviation these three objective evaluation parameters for the further analysis of the fusion result. Different low illumination environment experiments show that the algorithm in this paper can rapidly get wide dynamic range while keeping high entropy. Through the verification of this algorithm features, there is a further application prospect of the optimized algorithm. Keywords: high dynamic range imaging, image fusion, multi-exposure image, weight coefficient, information fusion, Laplacian pyramid transform.

Acute Seizures in Old Age Leads to a Greater Loss of CA1 Pyramidal Neurons, an Increased Propensity for Developing Chronic TLE and a Severe Cognitive Dysfunction.

PubMed

Hattiangady, Bharathi; Kuruba, Ramkumar; Shetty, Ashok K

2011-02-01

The aged population displays an enhanced risk for developing acute seizure (AS) activity. However, it is unclear whether AS activity in old age would result in a greater magnitude of hippocampal neurodegeneration and inflammation, and an increased predilection for developing chronic temporal lobe epilepsy (TLE) and cognitive dysfunction. Therefore, we addressed these issues in young-adult (5-months old) and aged (22-months old) F344 rats after three-hours of AS activity, induced through graded intraperitoneal injections of kainic acid (KA), and terminated through a diazepam injection. During the three-hours of AS activity, both young adult and aged groups exhibited similar numbers of stage-V motor seizures but the numbers of stage-IV motor seizures were greater in the aged group. In both age groups, three-hour AS activity induced degeneration of 50-55% of neurons in the dentate hilus, 22-32% of neurons in the granule cell layer and 49-52% neurons in the CA3 pyramidal cell layer without showing any interaction between the age and AS activity. However, degeneration of neurons in the CA1 pyramidal cell layer showed a clear interaction between the age and AS activity (12% in the young adult group and 56% in the aged group), suggesting that an advanced age makes the CA1 pyramidal neurons more susceptible to die with AS activity. The extent of inflammation measured through the numbers of activated microglial cells was similar between the two age groups. Interestingly, the predisposition for developing chronic TLE at 2-3 months after AS activity was 60% for young adult rats but 100% for aged rats. Moreover, both frequency & intensity of spontaneous recurrent seizures in the chronic phase after AS activity were 6-12 folds greater in aged rats than in young adult rats. Furthermore, aged rats lost their ability for spatial learning even in a scrupulous eleven-session water maze learning paradigm after AS activity, in divergence from young adult rats which retained the ability for spatial learning but had memory retrieval dysfunction after AS activity. Thus, AS activity in old age results in a greater loss of hippocampal CA1 pyramidal neurons, an increased propensity for developing robust chronic TLE, and a severe cognitive dysfunction.

Noradrenaline Modulates the Membrane Potential and Holding Current of Medial Prefrontal Cortex Pyramidal Neurons via β1-Adrenergic Receptors and HCN Channels.

PubMed

Grzelka, Katarzyna; Kurowski, Przemysław; Gawlak, Maciej; Szulczyk, Paweł

2017-01-01

The medial prefrontal cortex (mPFC) receives dense noradrenergic projections from the locus coeruleus. Adrenergic innervation of mPFC pyramidal neurons plays an essential role in both physiology (control of memory formation, attention, working memory, and cognitive behavior) and pathophysiology (attention deficit hyperactivity disorder, posttraumatic stress disorder, cognitive deterioration after traumatic brain injury, behavioral changes related to addiction, Alzheimer's disease and depression). The aim of this study was to elucidate the mechanism responsible for adrenergic receptor-mediated control of the resting membrane potential in layer V mPFC pyramidal neurons. The membrane potential or holding current of synaptically isolated layer V mPFC pyramidal neurons was recorded in perforated-patch and classical whole-cell configurations in slices from young rats. Application of noradrenaline (NA), a neurotransmitter with affinity for all types of adrenergic receptors, evoked depolarization or inward current in the tested neurons irrespective of whether the recordings were performed in the perforated-patch or classical whole-cell configuration. The effect of noradrenaline depended on β 1 - and not α 1 - or α 2 -adrenergic receptor stimulation. Activation of β 1 -adrenergic receptors led to an increase in inward Na + current through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which carry a mixed Na + /K + current. The protein kinase A- and C-, glycogen synthase kinase-3β- and tyrosine kinase-linked signaling pathways were not involved in the signal transduction between β 1 -adrenergic receptors and HCN channels. The transduction system operated in a membrane-delimited fashion and involved the βγ subunit of G-protein. Thus, noradrenaline controls the resting membrane potential and holding current in mPFC pyramidal neurons through β 1 -adrenergic receptors, which in turn activate HCN channels via a signaling pathway involving the βγ subunit.

Noradrenaline Modulates the Membrane Potential and Holding Current of Medial Prefrontal Cortex Pyramidal Neurons via β1-Adrenergic Receptors and HCN Channels

PubMed Central

Grzelka, Katarzyna; Kurowski, Przemysław; Gawlak, Maciej; Szulczyk, Paweł

2017-01-01

The medial prefrontal cortex (mPFC) receives dense noradrenergic projections from the locus coeruleus. Adrenergic innervation of mPFC pyramidal neurons plays an essential role in both physiology (control of memory formation, attention, working memory, and cognitive behavior) and pathophysiology (attention deficit hyperactivity disorder, posttraumatic stress disorder, cognitive deterioration after traumatic brain injury, behavioral changes related to addiction, Alzheimer’s disease and depression). The aim of this study was to elucidate the mechanism responsible for adrenergic receptor-mediated control of the resting membrane potential in layer V mPFC pyramidal neurons. The membrane potential or holding current of synaptically isolated layer V mPFC pyramidal neurons was recorded in perforated-patch and classical whole-cell configurations in slices from young rats. Application of noradrenaline (NA), a neurotransmitter with affinity for all types of adrenergic receptors, evoked depolarization or inward current in the tested neurons irrespective of whether the recordings were performed in the perforated-patch or classical whole-cell configuration. The effect of noradrenaline depended on β1- and not α1- or α2-adrenergic receptor stimulation. Activation of β1-adrenergic receptors led to an increase in inward Na+ current through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which carry a mixed Na+/K+ current. The protein kinase A- and C-, glycogen synthase kinase-3β- and tyrosine kinase-linked signaling pathways were not involved in the signal transduction between β1-adrenergic receptors and HCN channels. The transduction system operated in a membrane-delimited fashion and involved the βγ subunit of G-protein. Thus, noradrenaline controls the resting membrane potential and holding current in mPFC pyramidal neurons through β1-adrenergic receptors, which in turn activate HCN channels via a signaling pathway involving the βγ subunit. PMID:29209170

Role of Microglia Disturbances and Immune-Related Marker Abnormalities in Cortical Circuitry Dysfunction in Schizophrenia

PubMed Central

Volk, David W.

2017-01-01

Studies of genetics, serum cytokines, and autoimmune illnesses suggest that immune-related abnormalities are involved in the disease process of schizophrenia. Furthermore, direct evidence of cortical immune activation, including markedly elevated levels of many immune-related markers, have been reported in the prefrontal cortex in multiple cohorts of schizophrenia subjects. Within the prefrontal cortex in schizophrenia, deficits in the basilar dendritic spines of layer 3 pyramidal neurons and disturbances in inhibitory inputs to pyramidal neurons have also been commonly reported. Interestingly, microglia, the resident immune-related cells of the brain, also regulate excitatory and inhibitory input to pyramidal neurons. Consequently, in this review, we describe the cytological and molecular evidence of immune activation that has been reported in the brains of individuals with schizophrenia and the potential links between these immune-related disturbances with previously reported disturbances in pyramidal and inhibitory neurons in the disorder. Finally, we discuss the role that activated microglia may play in connecting these observations and as potential therapeutic treatment targets in schizophrenia. PMID:28007586

Excitation and inhibition compete to control spiking during hippocampal ripples: intracellular study in behaving mice.

PubMed

English, Daniel F; Peyrache, Adrien; Stark, Eran; Roux, Lisa; Vallentin, Daniela; Long, Michael A; Buzsáki, György

2014-12-03

High-frequency ripple oscillations, observed most prominently in the hippocampal CA1 pyramidal layer, are associated with memory consolidation. The cellular and network mechanisms underlying the generation of the rhythm and the recruitment of spikes from pyramidal neurons are still poorly understood. Using intracellular, sharp electrode recordings in freely moving, drug-free mice, we observed consistent large depolarizations in CA1 pyramidal cells during sharp wave ripples, which are associated with ripple frequency fluctuation of the membrane potential ("intracellular ripple"). Despite consistent depolarization, often exceeding pre-ripple spike threshold values, current pulse-induced spikes were strongly suppressed, indicating that spiking was under the control of concurrent shunting inhibition. Ripple events were followed by a prominent afterhyperpolarization and spike suppression. Action potentials during and outside ripples were orthodromic, arguing against ectopic spike generation, which has been postulated by computational models of ripple generation. These findings indicate that dendritic excitation of pyramidal neurons during ripples is countered by shunting of the membrane and postripple silence is mediated by hyperpolarizing inhibition. Copyright © 2014 the authors 0270-6474/14/3316509-09$15.00/0.

Spatial distribution of neurons innervated by chandelier cells.

PubMed

Blazquez-Llorca, Lidia; Woodruff, Alan; Inan, Melis; Anderson, Stewart A; Yuste, Rafael; DeFelipe, Javier; Merchan-Perez, Angel

2015-09-01

Chandelier (or axo-axonic) cells are a distinct group of GABAergic interneurons that innervate the axon initial segments of pyramidal cells and are thus thought to have an important role in controlling the activity of cortical circuits. To examine the circuit connectivity of chandelier cells (ChCs), we made use of a genetic targeting strategy to label neocortical ChCs in upper layers of juvenile mouse neocortex. We filled individual ChCs with biocytin in living brain slices and reconstructed their axonal arbors from serial semi-thin sections. We also reconstructed the cell somata of pyramidal neurons that were located inside the ChC axonal trees and determined the percentage of pyramidal neurons whose axon initial segments were innervated by ChC terminals. We found that the total percentage of pyramidal neurons that were innervated by a single labeled ChC was 18-22 %. Sholl analysis showed that this percentage peaked at 22-35 % for distances between 30 and 60 µm from the ChC soma, decreasing to lower percentages with increasing distances. We also studied the three-dimensional spatial distribution of the innervated neurons inside the ChC axonal arbor using spatial statistical analysis tools. We found that innervated pyramidal neurons are not distributed at random, but show a clustered distribution, with pockets where almost all cells are innervated and other regions within the ChC axonal tree that receive little or no innervation. Thus, individual ChCs may exert a strong, widespread influence on their local pyramidal neighbors in a spatially heterogeneous fashion.

High-resolution immunogold localization of AMPA type glutamate receptor subunits at synaptic and non-synaptic sites in rat hippocampus.

PubMed

Baude, A; Nusser, Z; Molnár, E; McIlhinney, R A; Somogyi, P

1995-12-01

The cellular and subcellular localization of the GluRA, GluRB/C and GluRD subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) type glutamate receptor was determined in the rat hippocampus using polyclonal antipeptide antibodies in immunoperoxidase and immunogold procedures. For the localization of the GluRD subunit a new polyclonal antiserum was developed using the C-terminal sequence of the protein (residues 869-881), conjugated to carrier protein and absorbed to colloidal gold for immunization. The purified antibodies immunoprecipitated about 25% of 3[H]AMPA binding activity from the hippocampus, cerebellum or whole brain, but very little from neocortex. These antibodies did not precipitate a significant amount of 3[H]kainate binding activity. The antibodies also recognize the GluRD subunit, but not the other AMPA receptor subunits, when expressed in transfected COS-7 cells and only when permeabilized with detergent, indicating an intracellular epitope. All subunits were enriched in the neuropil of the dendritic layers of the hippocampus and in the molecular layer of the dentate gyrus. The cellular distribution of the GluRD subunit was studied more extensively. The strata radiatum, oriens and the dentate molecular layer were more strongly immunoreactive than the stratum lacunosum moleculare, the stratum lucidum and the hilus. However, in the stratum lucidum of the CA3 area and in the hilus the weakly reacting dendrites were surrounded by immunopositive rosettes, shown in subsequent electron microscopic studies to correspond to complex dendritic spines. In the stratum radiatum, the weakly reacting apical dendrites contrasted with the surrounding intensely stained neuropil. The cell bodies of pyramidal and granule cells were moderately reactive. Some non-principal cells and their dendrites in the pyramidal cell layer and in the alveus also reacted very strongly for the GluRD subunit. At the subcellular level, silver intensified immunogold particles for the GluRA, GluRB/C and GluRD subunits were present at type 1 synaptic membrane specializations on dendritic spines of pyramidal cells throughout all layers of the CA1 and CA3 areas. The most densely labelled synapses tended to be on the largest spines and many smaller spines remained unlabelled. Immunoparticle density at type 1 synapses on dendritic shafts of some non-principal cells was consistently higher than at labelled synapses of dendritic spines of pyramidal cells. Synapses established between dendritic spines and mossy fibre terminals, were immunoreactive for all studied subunits in stratum lucidum of the CA3 area. The postembedding immunogold method revealed that the AMPA type receptors are concentrated within the main body of the anatomically defined type 1 (asymmetrical) synaptic junction. Often only a part of the membrane specialization showed clustered immunoparticles. There was a sharp decrease in immunoreactive receptor density at the edge of the synaptic specialization. Immunolabelling was consistently demonstrated at extrasynaptic sites on dendrites, dendritic spines and somata. The results demonstrate that the GluRA, B/C and D subunits of the AMPA type glutamate receptor are present in many of the glutamatergic synapses formed by the entorhinal, CA3 pyramidal and mossy fibre terminals. Some interneurons have a higher density of AMPA type receptors in their asymmetrical afferent synapses than pyramidal cells. This may contribute to a lower activation threshold of interneurons as compared to principal cells by the same afferents in the hippocampal formation.

Identified Cellular Correlates of Neocortical Ripple and High-Gamma Oscillations during Spindles of Natural Sleep.

PubMed

Averkin, Robert G; Szemenyei, Viktor; Bordé, Sándor; Tamás, Gábor

2016-11-23

Ultra-high-frequency network events in the hippocampus are instrumental in a dialogue with the neocortex during memory formation, but the existence of transient ∼200 Hz network events in the neocortex is not clear. Our recordings from neocortical layer II/III of freely behaving rats revealed field potential events at ripple and high-gamma frequencies repeatedly occurring at troughs of spindle oscillations during sleep. Juxtacellular recordings identified subpopulations of fast-spiking, parvalbumin-containing basket cells with epochs of firing at ripple (∼200 Hz) and high-gamma (∼120 Hz) frequencies detected during spindles and centered with millisecond precision at the trough of spindle waves in phase with field potential events but phase shifted relative to pyramidal cell firing. The results suggest that basket cell subpopulations are involved in spindle-nested, high-frequency network events that hypothetically provide repeatedly occurring neocortical temporal reference states potentially involved in mnemonic processes. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Time Resolved Tomographic PIV Measurements of Rough-Wall Turbulent Channel Flow

NASA Astrophysics Data System (ADS)

Miorini, Rinaldo; Zhang, Cao; Katz, Joseph

2013-11-01

Time resolved tomographic PIV is used to study flow structures in the outer region of a rough-wall turbulent boundary layer, focusing on imprints of the roughness on the outer layer. Measurements are performed in a transparent channel installed in the JHU optically index matched facility. The roughness consists of pyramids with height, k = 0.46 mm, and wavelength, λ = 3.2 mm, satisfying h/k = 55 (h = 25.4 mm is the channel half-height), k + = 64 and Re = 40000. The TPIV setup consists of four high-speed cameras operating at 3 kHz, which view the sample volume through acrylic prisms. The flow field is illuminated by an Nd:YLF laser. Following enhancement, calibration, and reconstruction, 643 voxels interrogation volumes with 0.75 overlap provide 3D velocity fields with spacing of 0.5883 mm3. Formation and transport of near-wall 3D U-shaped vortex structures, with base in front of the pyramids, and quasi-streamwise legs extending between pyramid crest lines are evident from the data. Extended streamwise regions of high wall-normal vorticity appear ``latched'' to the roughness elements close to the wall, but are transported downstream at higher elevations. Also evident are traveling streamwise low velocity streaks, which cover many roughness elements. Sponsored by NSF CBET and ONR.

Towards deep learning with segregated dendrites

PubMed Central

Guerguiev, Jordan; Lillicrap, Timothy P

2017-01-01

Deep learning has led to significant advances in artificial intelligence, in part, by adopting strategies motivated by neurophysiology. However, it is unclear whether deep learning could occur in the real brain. Here, we show that a deep learning algorithm that utilizes multi-compartment neurons might help us to understand how the neocortex optimizes cost functions. Like neocortical pyramidal neurons, neurons in our model receive sensory information and higher-order feedback in electrotonically segregated compartments. Thanks to this segregation, neurons in different layers of the network can coordinate synaptic weight updates. As a result, the network learns to categorize images better than a single layer network. Furthermore, we show that our algorithm takes advantage of multilayer architectures to identify useful higher-order representations—the hallmark of deep learning. This work demonstrates that deep learning can be achieved using segregated dendritic compartments, which may help to explain the morphology of neocortical pyramidal neurons. PMID:29205151

Towards deep learning with segregated dendrites.

PubMed

Guerguiev, Jordan; Lillicrap, Timothy P; Richards, Blake A

2017-12-05

Deep learning has led to significant advances in artificial intelligence, in part, by adopting strategies motivated by neurophysiology. However, it is unclear whether deep learning could occur in the real brain. Here, we show that a deep learning algorithm that utilizes multi-compartment neurons might help us to understand how the neocortex optimizes cost functions. Like neocortical pyramidal neurons, neurons in our model receive sensory information and higher-order feedback in electrotonically segregated compartments. Thanks to this segregation, neurons in different layers of the network can coordinate synaptic weight updates. As a result, the network learns to categorize images better than a single layer network. Furthermore, we show that our algorithm takes advantage of multilayer architectures to identify useful higher-order representations-the hallmark of deep learning. This work demonstrates that deep learning can be achieved using segregated dendritic compartments, which may help to explain the morphology of neocortical pyramidal neurons.

Chrna2-Martinotti Cells Synchronize Layer 5 Type A Pyramidal Cells via Rebound Excitation

PubMed Central

Leão, Richardson N.; Edwards, Steven J.

2017-01-01

Martinotti cells are the most prominent distal dendrite–targeting interneurons in the cortex, but their role in controlling pyramidal cell (PC) activity is largely unknown. Here, we show that the nicotinic acetylcholine receptor α2 subunit (Chrna2) specifically marks layer 5 (L5) Martinotti cells projecting to layer 1. Furthermore, we confirm that Chrna2-expressing Martinotti cells selectively target L5 thick-tufted type A PCs but not thin-tufted type B PCs. Using optogenetic activation and inhibition, we demonstrate how Chrna2-Martinotti cells robustly reset and synchronize type A PCs via slow rhythmic burst activity and rebound excitation. Moreover, using optical feedback inhibition, in which PC spikes controlled the firing of surrounding Chrna2-Martinotti cells, we found that neighboring PC spike trains became synchronized by Martinotti cell inhibition. Together, our results show that L5 Martinotti cells participate in defined cortical circuits and can synchronize PCs in a frequency-dependent manner. These findings suggest that Martinotti cells are pivotal for coordinated PC activity, which is involved in cortical information processing and cognitive control. PMID:28182735

Evidence for Kinetic Limitations as a Controlling Factor of Ge Pyramid Formation: a Study of Structural Features of Ge/Si(001) Wetting Layer Formed by Ge Deposition at Room Temperature Followed by Annealing at 600 °C.

PubMed

Storozhevykh, Mikhail S; Arapkina, Larisa V; Yuryev, Vladimir A

2015-12-01

The article presents an experimental study of an issue of whether the formation of arrays of Ge quantum dots on the Si(001) surface is an equilibrium process or it is kinetically controlled. We deposited Ge on Si(001) at the room temperature and explored crystallization of the disordered Ge film as a result of annealing at 600 °C. The experiment has demonstrated that the Ge/Si(001) film formed in the conditions of an isolated system consists of the standard patched wetting layer and large droplike clusters of Ge rather than of huts or domes which appear when a film is grown in a flux of Ge atoms arriving on its surface. We conclude that the growth of the pyramids appearing at temperatures greater than 600 °C is controlled by kinetics rather than thermodynamic equilibrium whereas the wetting layer is an equilibrium structure. Primary 68.37.Ef; 68.55.Ac; 68.65.Hb; 81.07.Ta; 81.16.Dn.

Pyramidal defects in highly Mg-doped GaN: atomic structure and influence on optoelectronic properties

NASA Astrophysics Data System (ADS)

Leroux, M.; Vennéguès, P.; Dalmasso, S.; de Mierry, P.; Lorenzini, P.; Damilano, B.; Beaumont, B.; Gibart, P.; Massies, J.

2004-07-01

A detailed transmission electron microscopy study is performed on the pyramidal inversion domains that appear in highly Mg-doped GaN grown by metalorganics vapor phase epitaxy or by the high-pressure, high-temperature method. From a comparison between high resolution images of the inversion domain boundaries and simulations using different atomic models, we conclude that both basal and inclined domain boundaries are likely formed of a monomolecular layer of the definite compound Mg{3}N{2}. We show that, due to their high concentration, the formation of these defects may account for auto-compensation in Mg-doped GaN. We also show that the local band bending induced by the polarity inversion due to these defects can be at the origin of the blue luminescence of highly Mg-doped GaN, always observed when nanometric pyramidal inversion domains are also present.

Synthesis and spectroscopic studies of biologically active compounds derived from oxalyldihydrazide and benzil, and their Cr(III), Fe(III) and Mn(III) complexes.

PubMed

Singh, D P; Kumar, Ramesh; Singh, Jitender

2009-04-01

A new series of complexes have been synthesized by template condensation of oxalyldihydrazide and benzil in methanolic medium in the presence of trivalent chromium, manganese and iron salts forming complexes of the type [M(C(32)H(24)N(8)O(4))X]X(2) where M = Cr(III), Mn(III), Fe(III) and X = Cl(-1), NO(3)(-1), CH(3)COO(-1). The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic susceptibility measurements, electronic, NMR, infrared and far infrared spectral studies. On the basis of these studies, a five coordinate square pyramidal geometry has been proposed for all these complexes. The biological activities of the metal complexes have been tested in vitro against a number of pathogenic bacteria to assess their inhibiting potential. Some of these complexes have been found to exhibit remarkable antibacterial activities.

Relationships between morphology and physiology of pyramid-pyramid single axon connections in rat neocortex in vitro.

PubMed Central

Deuchars, J; West, D C; Thomson, A M

1994-01-01

1. Double intracellular recordings were made from 1163 pairs of pyramidal neurones in layer V-VI of the rat somatomotor cortex in vitro using sharp electrodes filled with biocytin. Monosynaptically connected pairs of cells were identified when an action potential in one could elicit a constant latency excitatory postsynaptic potential (EPSP) in the other and the cells were filled with biocytin. Labelled cells were subsequently identified histologically with avidin-horseradish peroxidase. 2. Thirty-four pairs of cells were found to be monosynaptically connected. Fifteen of these pairs were sufficiently stable for electrophysiological recordings and three of these were recovered sufficiently to permit full morphological reconstruction. 3. The EPSP recorded between the first pair of pyramids varied in amplitude between 0 and 3 mV (mean 1.33 +/- 1.06 mV) and fluctuated considerably (coefficient of variation, 0.796). This was largely due to a high incidence of apparent failures of transmission. On reconstruction two boutons from the presynaptic pyramid axon were in close apposition to the proximal portions of basal dendrites of the postsynaptic cell. 4. In the second pair of pyramids the EPSP had a mean amplitude of 1.06 mV, and displayed a 10-90% rise time of 2.8 ms and a width at half-amplitude of 23 ms. This EPSP did not alter significantly with changes in membrane potential at the soma. The presynaptic axon closely apposed the distal apical dendrite of the postsynaptic cell in eight places. 5. In the third pair of pyramids, the EPSPs, recorded at a relatively depolarized membrane potential, were long lasting and could elicit slow dendritic spikes with long and variable latencies. These slow spikes suggested that the postsynaptic recording site was dendritic and on reconstruction a possible location was identified on the apical dendrite. A total of five presynaptic boutons closely apposed three separate, proximal branches of the postsynaptic apical dendrite. 6. These results provide the first illustration of a morphological basis for variations in functional properties of pyramid-pyramid connections in the neocortex. Images Figure 1 Figure 3 Figure 5 PMID:7965856

MBE Growth of InN/GaN(0001) and Shape Transitions of InN islands

NASA Astrophysics Data System (ADS)

Cao, Yongge; Xie, Maohai; Liu, Ying; Ng, Y. F.

2003-03-01

Plasma-assisted molecular-beam epitaxial growth of InN on GaN(0001) is investigated. Both layer-by-layer and Stranski-Krastanov (SK) growth modes are observed under different growth windows. Strain relaxation is studied by real-time recording of the in-plane lattice spacing evolutions on RHEED pattern, which suggest a gradual relaxation of the strain in InN film commenced during the first bilayer (BL) deposition and almost completed after 2-4 BLs. For SK growth, 3D islanding initiates after the strain has mostly been relieved, presumably by dislocations. Based on statistical analysis, the shape transitions of 3D islands are firstly observed in the III-nitrides system. The InN islands transform gradually from pyramids to platelets with increasing of In flux. Under In-rich growth condition, the reverse trend of island shape evolution dependence on volume size, compared with Equilibrium Crystal Shape (ECS) theory, is induced by the Indium self-surfactant effects, in which Indium adlayer on the top surface of InN islands will depress the thermodynamic driving force for the vertical growth of 3D islands. Lateral growth of 3D islands is not only the result of kinetic process but also favored by thermodynamics while Indium self-surfactant exist.

Acetylcholine Mediates a Slow Synaptic Potential in Hippocampal Pyramidal Cells

NASA Astrophysics Data System (ADS)

Cole, A. E.; Nicoll, R. A.

1983-09-01

The hippocampal slice preparation was used to study the role of acetylcholine as a synaptic transmitter. Bath-applied acetylcholine had three actions on pyramidal cells: (i) depolarization associated with increased input resistance, (ii) blockade of calcium-activated potassium responses, and (iii) blockade of accommodation of cell discharge. All these actions were reversed by the muscarinic antagonist atropine. Stimulation of sites in the slice known to contain cholinergic fibers mimicked all the actions. Furthermore, these evoked synaptic responses were enhanced by the cholinesterase inhibitor eserine and were blocked by atropine. These findings provide electrophysiological support for the role of acetylcholine as a synaptic transmitter in the brain and demonstrate that nonclassical synaptic responses involving the blockade of membrane conductances exist in the brain.

Neurons of the Dentate Molecular Layer in the Rabbit Hippocampus

PubMed Central

Sancho-Bielsa, Francisco J.; Navarro-López, Juan D.; Alonso-Llosa, Gregori; Molowny, Asunción; Ponsoda, Xavier; Yajeya, Javier; López-García, Carlos

2012-01-01

The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals’ life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow and biocytin injections), eight neuronal morphological types have been detected in the molecular layer of developing adult and old rabbits. Six of them appear as interneurons displaying smooth dendrites and GABA immunoreactivity: those here called as globoid, vertical, small horizontal, large horizontal, inverted pyramidal and polymorphic. Additionally there are two GABA negative types: the sarmentous and ectopic granular neurons. The distribution of the somata and dendritic trees of these neurons shows preferences for a definite sublayer of the molecular layer: small horizontal, sarmentous and inverted pyramidal neurons are preferably found in the outer third of the molecular layer; vertical, globoid and polymorph neurons locate the intermediate third, while large horizontal and ectopic granular neurons occupy the inner third or the juxtagranular molecular layer. Our results reveal substantial differences in the morphology and electrophysiological behaviour between each neuronal archetype in the dentate molecular layer, allowing us to propose a new classification for this neural population. PMID:23144890

Neurons of the dentate molecular layer in the rabbit hippocampus.

PubMed

Sancho-Bielsa, Francisco J; Navarro-López, Juan D; Alonso-Llosa, Gregori; Molowny, Asunción; Ponsoda, Xavier; Yajeya, Javier; López-García, Carlos

2012-01-01

The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals' life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow and biocytin injections), eight neuronal morphological types have been detected in the molecular layer of developing adult and old rabbits. Six of them appear as interneurons displaying smooth dendrites and GABA immunoreactivity: those here called as globoid, vertical, small horizontal, large horizontal, inverted pyramidal and polymorphic. Additionally there are two GABA negative types: the sarmentous and ectopic granular neurons. The distribution of the somata and dendritic trees of these neurons shows preferences for a definite sublayer of the molecular layer: small horizontal, sarmentous and inverted pyramidal neurons are preferably found in the outer third of the molecular layer; vertical, globoid and polymorph neurons locate the intermediate third, while large horizontal and ectopic granular neurons occupy the inner third or the juxtagranular molecular layer. Our results reveal substantial differences in the morphology and electrophysiological behaviour between each neuronal archetype in the dentate molecular layer, allowing us to propose a new classification for this neural population.

Mechanism and energetics of dislocation cross-slip in hcp metals

NASA Astrophysics Data System (ADS)

Wu, Zhaoxuan; Curtin, W. A.

2016-10-01

Hexagonal close-packed (hcp) metals such as Mg, Ti, and Zr are lightweight and/or durable metals with critical structural applications in the automotive (Mg), aerospace (Ti), and nuclear (Zr) industries. The hcp structure, however, brings significant complications in the mechanisms of plastic deformation, strengthening, and ductility, and these complications pose significant challenges in advancing the science and engineering of these metals. In hcp metals, generalized plasticity requires the activation of slip on pyramidal planes, but the structure, motion, and cross-slip of the associated dislocations are not well established even though they determine ductility and influence strengthening. Here, atomistic simulations in Mg reveal the unusual mechanism of dislocation cross-slip between pyramidal I and II planes, which occurs by cross-slip of the individual partial dislocations. The energy barrier is controlled by a fundamental step/jog energy and the near-core energy difference between pyramidal dislocations. The near-core energy difference can be changed by nonglide stresses, leading to tension-compression asymmetry and even a switch in absolute stability from one glide plane to the other, both features observed experimentally in Mg, Ti, and their alloys. The unique cross-slip mechanism is governed by common features of the generalized stacking fault energy surfaces of hcp pyramidal planes and is thus expected to be generic to all hcp metals. An analytical model is developed to predict the cross-slip barrier as a function of the near-core energy difference and applied stresses and quantifies the controlling features of cross-slip and pyramidal I/II stability across the family of hcp metals.

Kinetic properties and adrenergic control of TREK-2-like channels in rat medial prefrontal cortex (mPFC) pyramidal neurons.

PubMed

Ładno, W; Gawlak, M; Szulczyk, P; Nurowska, E

2017-06-15

TREK-2-like channels were identified on the basis of electrophysiological and pharmacological tests performed on freshly isolated and enzymatically/mechanically dispersed pyramidal neurons of the rat medial prefrontal cortex (mPFC). Single-channel currents were recorded in cell-attached configuration and the impact of adrenergic receptors (α 1 , α 2 , β) stimulation on spontaneously appearing TREK-2-like channel activity was tested. The obtained results indicate that noradrenaline decreases the mean open probability of TREK-2-like channel currents by activation of β 1 but not of α 1 - and α 2 -adrenergic receptors. Mean open time and channel conductance were not affected. The system of intracellular signaling pathways depends on the activation of protein kinase A. We also show that adrenergic control of TREK-2-like channel currents by adrenergic receptors was similar in pyramidal neurons isolated from young, adolescent, and adult rats. Immunofluorescent confocal scans of mPFC slices confirmed the presence of the TREK-2 protein, which was abundant in layer V pyramidal neurons. The role of TREK-2-like channel control by adrenergic receptors is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

A Realistic Neural Mass Model of the Cortex with Laminar-Specific Connections and Synaptic Plasticity – Evaluation with Auditory Habituation

PubMed Central

Wang, Peng; Knösche, Thomas R.

2013-01-01

In this work we propose a biologically realistic local cortical circuit model (LCCM), based on neural masses, that incorporates important aspects of the functional organization of the brain that have not been covered by previous models: (1) activity dependent plasticity of excitatory synaptic couplings via depleting and recycling of neurotransmitters and (2) realistic inter-laminar dynamics via laminar-specific distribution of and connections between neural populations. The potential of the LCCM was demonstrated by accounting for the process of auditory habituation. The model parameters were specified using Bayesian inference. It was found that: (1) besides the major serial excitatory information pathway (layer 4 to layer 2/3 to layer 5/6), there exists a parallel “short-cut” pathway (layer 4 to layer 5/6), (2) the excitatory signal flow from the pyramidal cells to the inhibitory interneurons seems to be more intra-laminar while, in contrast, the inhibitory signal flow from inhibitory interneurons to the pyramidal cells seems to be both intra- and inter-laminar, and (3) the habituation rates of the connections are unsymmetrical: forward connections (from layer 4 to layer 2/3) are more strongly habituated than backward connections (from Layer 5/6 to layer 4). Our evaluation demonstrates that the novel features of the LCCM are of crucial importance for mechanistic explanations of brain function. The incorporation of these features into a mass model makes them applicable to modeling based on macroscopic data (like EEG or MEG), which are usually available in human experiments. Our LCCM is therefore a valuable building block for future realistic models of human cognitive function. PMID:24205009

Increased Cortical Inhibition in Autism-Linked Neuroligin-3R451C Mice Is Due in Part to Loss of Endocannabinoid Signaling.

PubMed

Speed, Haley E; Masiulis, Irene; Gibson, Jay R; Powell, Craig M

2015-01-01

A single, maternally inherited, X-linked point mutation leading to an arginine to cysteine substitution at amino acid 451 (R451C) of Neuroligin 3 (NLGN3R451C) is a likely cause of autism in two brothers. Knockin mice expressing the Nlgn3R451C mutation in place of wild-type Nlgn3 demonstrate increased inhibitory synaptic strength in somatosensory cortex, resulting in an excitatory/inhibitory (E/I) imbalance that is potentially relevant for autism-associated behavioral deficits characteristic of these mice. We have replicated the increase in evoked inhibitory postsynaptic currents (eIPSCs) onto layer II/III cortical pyramidal neurons. We also find that increased frequency of spontaneous mIPSCs in Nlgn3R451C mice occurs in the absence of action potential-driven transmission. This suggests the E/I imbalance is due to changes at the synapse level, as opposed to the network level. Next, we use paired whole-cell recordings in an attempt to identify specific interneuron subtypes affected by the Nlgn3R451C mutation. Curiously, we observe no change in the amplitude of cell-to-cell, unitary IPSCs (uIPSCs) from parvalbumin-positive (PV) or somatostatin-positive (SOM) interneurons onto pyramidal neurons. We also observe no change in the number or density of PV and SOM interneurons in LII/III of somatosensory cortex. This effectively rules out a role for these particular interneurons in the increased inhibitory synaptic transmission, pointing to perhaps alternative interneuron subtypes. Lastly, impaired endocannabinoid signaling has been implicated in hippocampal synaptic dysfunction in Nlgn3R451C mice, but has not been investigated at cortical synapses. We find that bath application of the CB1 antagonist, AM 251 in WT mice eliminates the Nlgn3R451C increase in eIPSC amplitude and mIPSC frequency, indicating that increased inhibitory transmission in mutant mice is due, at least in part, to a loss of endocannabinoid signaling through CB1 receptors likely acting at interneurons other than PV or SOM.

Increased Cortical Inhibition in Autism-Linked Neuroligin-3R451C Mice Is Due in Part to Loss of Endocannabinoid Signaling

PubMed Central

Speed, Haley E.; Masiulis, Irene; Gibson, Jay R.; Powell, Craig M.

2015-01-01

A single, maternally inherited, X-linked point mutation leading to an arginine to cysteine substitution at amino acid 451 (R451C) of Neuroligin 3 (NLGN3R451C) is a likely cause of autism in two brothers. Knockin mice expressing the Nlgn3R451C mutation in place of wild-type Nlgn3 demonstrate increased inhibitory synaptic strength in somatosensory cortex, resulting in an excitatory/inhibitory (E/I) imbalance that is potentially relevant for autism-associated behavioral deficits characteristic of these mice. We have replicated the increase in evoked inhibitory postsynaptic currents (eIPSCs) onto layer II/III cortical pyramidal neurons. We also find that increased frequency of spontaneous mIPSCs in Nlgn3R451C mice occurs in the absence of action potential-driven transmission. This suggests the E/I imbalance is due to changes at the synapse level, as opposed to the network level. Next, we use paired whole-cell recordings in an attempt to identify specific interneuron subtypes affected by the Nlgn3R451C mutation. Curiously, we observe no change in the amplitude of cell-to-cell, unitary IPSCs (uIPSCs) from parvalbumin-positive (PV) or somatostatin-positive (SOM) interneurons onto pyramidal neurons. We also observe no change in the number or density of PV and SOM interneurons in LII/III of somatosensory cortex. This effectively rules out a role for these particular interneurons in the increased inhibitory synaptic transmission, pointing to perhaps alternative interneuron subtypes. Lastly, impaired endocannabinoid signaling has been implicated in hippocampal synaptic dysfunction in Nlgn3R451C mice, but has not been investigated at cortical synapses. We find that bath application of the CB1 antagonist, AM 251 in WT mice eliminates the Nlgn3R451C increase in eIPSC amplitude and mIPSC frequency, indicating that increased inhibitory transmission in mutant mice is due, at least in part, to a loss of endocannabinoid signaling through CB1 receptors likely acting at interneurons other than PV or SOM. PMID:26469287

Photoinduced Cobalt(III)-Trifluoromethyl Bond Activation Enables Arene C-H Trifluoromethylation.

PubMed

Harris, Caleb F; Kuehner, Christopher S; Bacsa, John; Soper, Jake D

2018-01-26

Visible-light capture activates a thermodynamically inert Co III -CF 3 bond for direct C-H trifluoromethylation of arenes and heteroarenes. New trifluoromethylcobalt(III) complexes supported by a redox-active [OCO] pincer ligand were prepared. Coordinating solvents, such as MeCN, afford green, quasi-octahedral [( S OCO)Co III (CF 3 )(MeCN) 2 ] (2), but in non-coordinating solvents the complex is red, square pyramidal [( S OCO)Co III (CF 3 )(MeCN)] (3). Both are thermally stable, and 2 is stable in light. But exposure of 3 to low-energy light results in facile homolysis of the Co III -CF 3 bond, releasing . CF 3 radical, which is efficiently trapped by TEMPO . or (hetero)arenes. The homolytic aromatic substitution reactions do not require a sacrificial or substrate-derived oxidant because the Co II by-product of Co III -CF 3 homolysis produces H 2 . The photophysical properties of 2 and 3 provide a rationale for the disparate light stability. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Switchable Super-Hydrophilic/Hydrophobic Indium Tin Oxide (ITO) Film Surfaces on Reactive Ion Etching (RIE) Textured Si Wafer.

PubMed

Kim, Hwa-Min; Litao, Yao; Kim, Bonghwan

2015-11-01

We have developed a surface texturing process for pyramidal surface features along with an indium tin oxide (ITO) coating process to fabricate super-hydrophilic conductive surfaces. The contact angle of a water droplet was less than 5 degrees, which means that an extremely high wettability is achievable on super-hydrophilic surfaces. We have also fabricated a super-hydrophobic conductive surface using an additional coating of polytetrafluoroethylene (PTFE) on the ITO layer coated on the textured Si surface; the ITO and PTFE films were deposited by using a conventional sputtering method. We found that a super-hydrophilic conductive surface is produced by ITO coated on the pyramidal Si surface (ITO/Si), with contact angles of approximately 0 degrees and a resistivity of 3 x 10(-4) Ω x cm. These values are highly dependent on the substrate temperature during the sputtering process. We also found that the super-hydrophobic conductive surface produced by the additional coating of PTFE on the pyramidal Si surface with an ITO layer (PTFE/ITO/Si) has a contact angle of almost 160 degrees and a resistivity of 3 x 10(-4) Ω x cm, with a reflectance lower than 9%. Therefore, these processes can be used to fabricate multifunctional features of ITO films for switchable super-hydrophilic and super-hydrophobic surfaces.

Large variability in synaptic N-methyl-D-aspartate receptor density on interneurons and a comparison with pyramidal-cell spines in the rat hippocampus.

PubMed

Nyíri, G; Stephenson, F A; Freund, T F; Somogyi, P

2003-01-01

Pyramidal cells receive input from several types of GABA-releasing interneurons and innervate them reciprocally. Glutamatergic activation of interneurons involves both alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) type glutamate receptors expressed in type I synapses, mostly on their dendritic shafts. On average, the synaptic AMPA receptor content is several times higher on interneurons than in the spines of pyramidal cells. To compare the NMDA receptor content of synapses, we used a quantitative postembedding immunogold technique on serial electron microscopic sections, and analysed the synapses on interneuron dendrites and pyramidal cell spines in the CA1 area. Because all NMDA receptors contain the obligatory NR1 subunit, receptor localisation was carried out using antibodies recognising all splice variants of the NR1 subunit. Four populations of synapse were examined: i). on spines of pyramidal cells in stratum (str.) radiatum and str. oriens; ii). on parvalbumin-positive interneuronal dendritic shafts in str. radiatum; iii). on randomly found dendritic shafts in str. oriens and iv). on somatostatin-positive interneuronal dendritic shafts and somata in str. oriens. On average, the size of the synapses on spines was about half of those on interneurons. The four populations of synapse significantly differed in labelling for the NR1 subunit. The median density of NR1 subunit labelling was highest on pyramidal cell spines. It was lowest in the synapses on parvalbumin-positive dendrites in str. radiatum, where more than half of these synapses were immunonegative. In str. oriens, synapses on interneurons had a high variability of receptor content; some dendrites were similar to those in str. radiatum, including the proximal synapses of somatostatin-positive cells, whereas others had immunoreactivity for the NR1 subunit similar to or higher than synapses on pyramidal cell spines. These results show that synaptic NMDA receptor density differs between pyramidal cells and interneurons. Some interneurons may have a high NMDA receptor content, whereas others, like some parvalbumin-expressing cells, a particularly low synaptic NMDA receptor content. Consequently, fast glutamatergic activation of interneurons is expected to show cell type-specific time course and state-dependent dynamics.

Evidence for Kinetic Limitations as a Controlling Factor of Ge Pyramid Formation: a Study of Structural Features of Ge/Si(001) Wetting Layer Formed by Ge Deposition at Room Temperature Followed by Annealing at 600 °C

NASA Astrophysics Data System (ADS)

Storozhevykh, Mikhail S.; Arapkina, Larisa V.; Yuryev, Vladimir A.

2015-07-01

The article presents an experimental study of an issue of whether the formation of arrays of Ge quantum dots on the Si(001) surface is an equilibrium process or it is kinetically controlled. We deposited Ge on Si(001) at the room temperature and explored crystallization of the disordered Ge film as a result of annealing at 600 °C. The experiment has demonstrated that the Ge/Si(001) film formed in the conditions of an isolated system consists of the standard patched wetting layer and large droplike clusters of Ge rather than of huts or domes which appear when a film is grown in a flux of Ge atoms arriving on its surface. We conclude that the growth of the pyramids appearing at temperatures greater than 600 °C is controlled by kinetics rather than thermodynamic equilibrium whereas the wetting layer is an equilibrium structure. PACS: Primary 68.37.Ef; 68.55.Ac; 68.65.Hb; 81.07.Ta; 81.16.Dn

Nucleation mechanisms of epitaxial GaN nanowires: Origin of their self-induced formation and initial radius

NASA Astrophysics Data System (ADS)

Consonni, V.; Knelangen, M.; Geelhaar, L.; Trampert, A.; Riechert, H.

2010-02-01

The formation mechanisms of epitaxial GaN nanowires grown within a self-induced approach by molecular-beam epitaxy have been investigated at the onset of the nucleation process by combining in situ reflection high-energy electron-diffraction measurements and ex situ high-resolution transmission electron microscopy imaging. It is shown that the self-induced growth of GaN nanowires on the AlN buffer layer is initially governed by the nucleation of dislocation-free coherent islands. These coherent islands develop through a series of shape transitions from spherical caps through truncated to full pyramids in order to elastically relieve the lattice-mismatch-induced strain. A strong correlation between the subsequent process of plastic relaxation and the final shape transition from full pyramids toward the very first nanowires is found. The experimental critical radius at which the misfit dislocation nucleates is in very good agreement with the theoretical critical radius for the formation of the misfit dislocation in full pyramids, showing that the plastic relaxation process does take place within full pyramids: this critical size corresponds to the initial radius of the very first nanowires. We associate the plastic relaxation of the lattice-mismatch-induced strain occurring within full pyramids with a drastic change in their total free energy: this gives rise to a driving force for the shape transition toward the very first nanowires, which is mainly due to the anisotropy of surface energy.

An N-methyl-D-aspartate receptor-independent excitatory action of partial reduction of extracellular [Mg2+] in CA1-region of rat hippocampal slices.

PubMed

Hamon, B; Stanton, P K; Heinemann, U

1987-03-31

Partial reduction of [Mg2+]o from 2 to 1 mM markedly enhanced neuronal responses evoked by Schaffer collateral-commissural fiber stimulation in the CA1-region of rat hippocampal slices. The amplitude of extracellular population potentials recorded in the CA1-pyramidal cell layer and maximum dV/dt of extracellular population EPSP's recorded in the CA1-pyramidal apical dendritic layer were both increased. However, unlike findings from slices where Mg2+ was completely removed from the bathing medium, there was no spontaneous or evoked epileptiform activity, and the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonovalerate (2-APV) did not antagonize the enhancement of evoked responses. These results indicate that, in addition to the participation of NMDA receptors in the epileptiform activity observed when Mg2+ is completely removed from the bathing medium, there is also an NMDA receptor-independent excitatory action of partial reduction of [Mg2+]o in hippocampal slices.

Three Types of Cortical Layer 5 Neurons That Differ in Brain-wide Connectivity and Function.

PubMed

Kim, Euiseok J; Juavinett, Ashley L; Kyubwa, Espoir M; Jacobs, Matthew W; Callaway, Edward M

2015-12-16

Cortical layer 5 (L5) pyramidal neurons integrate inputs from many sources and distribute outputs to cortical and subcortical structures. Previous studies demonstrate two L5 pyramid types: cortico-cortical (CC) and cortico-subcortical (CS). We characterize connectivity and function of these cell types in mouse primary visual cortex and reveal a new subtype. Unlike previously described L5 CC and CS neurons, this new subtype does not project to striatum [cortico-cortical, non-striatal (CC-NS)] and has distinct morphology, physiology, and visual responses. Monosynaptic rabies tracing reveals that CC neurons preferentially receive input from higher visual areas, while CS neurons receive more input from structures implicated in top-down modulation of brain states. CS neurons are also more direction-selective and prefer faster stimuli than CC neurons. These differences suggest distinct roles as specialized output channels, with CS neurons integrating information and generating responses more relevant to movement control and CC neurons being more important in visual perception. Copyright © 2015 Elsevier Inc. All rights reserved.

Mechanism and energetics of 〈c + a〉 dislocation cross-slip in hcp metals.

PubMed

Wu, Zhaoxuan; Curtin, W A

2016-10-04

Hexagonal close-packed (hcp) metals such as Mg, Ti, and Zr are lightweight and/or durable metals with critical structural applications in the automotive (Mg), aerospace (Ti), and nuclear (Zr) industries. The hcp structure, however, brings significant complications in the mechanisms of plastic deformation, strengthening, and ductility, and these complications pose significant challenges in advancing the science and engineering of these metals. In hcp metals, generalized plasticity requires the activation of slip on pyramidal planes, but the structure, motion, and cross-slip of the associated [Formula: see text] dislocations are not well established even though they determine ductility and influence strengthening. Here, atomistic simulations in Mg reveal the unusual mechanism of [Formula: see text] dislocation cross-slip between pyramidal I and II planes, which occurs by cross-slip of the individual partial dislocations. The energy barrier is controlled by a fundamental step/jog energy and the near-core energy difference between pyramidal [Formula: see text] dislocations. The near-core energy difference can be changed by nonglide stresses, leading to tension-compression asymmetry and even a switch in absolute stability from one glide plane to the other, both features observed experimentally in Mg, Ti, and their alloys. The unique cross-slip mechanism is governed by common features of the generalized stacking fault energy surfaces of hcp pyramidal planes and is thus expected to be generic to all hcp metals. An analytical model is developed to predict the cross-slip barrier as a function of the near-core energy difference and applied stresses and quantifies the controlling features of cross-slip and pyramidal I/II stability across the family of hcp metals.

Mechanism and energetics of 〈c + a〉 dislocation cross-slip in hcp metals

PubMed Central

Wu, Zhaoxuan; Curtin, W. A.

2016-01-01

Hexagonal close-packed (hcp) metals such as Mg, Ti, and Zr are lightweight and/or durable metals with critical structural applications in the automotive (Mg), aerospace (Ti), and nuclear (Zr) industries. The hcp structure, however, brings significant complications in the mechanisms of plastic deformation, strengthening, and ductility, and these complications pose significant challenges in advancing the science and engineering of these metals. In hcp metals, generalized plasticity requires the activation of slip on pyramidal planes, but the structure, motion, and cross-slip of the associated 〈c+a〉 dislocations are not well established even though they determine ductility and influence strengthening. Here, atomistic simulations in Mg reveal the unusual mechanism of 〈c+a〉 dislocation cross-slip between pyramidal I and II planes, which occurs by cross-slip of the individual partial dislocations. The energy barrier is controlled by a fundamental step/jog energy and the near-core energy difference between pyramidal 〈c+a〉 dislocations. The near-core energy difference can be changed by nonglide stresses, leading to tension–compression asymmetry and even a switch in absolute stability from one glide plane to the other, both features observed experimentally in Mg, Ti, and their alloys. The unique cross-slip mechanism is governed by common features of the generalized stacking fault energy surfaces of hcp pyramidal planes and is thus expected to be generic to all hcp metals. An analytical model is developed to predict the cross-slip barrier as a function of the near-core energy difference and applied stresses and quantifies the controlling features of cross-slip and pyramidal I/II stability across the family of hcp metals. PMID:27647908

Fabrication of large area nanoprism arrays and their application for surface enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Cui, B.; Clime, L.; Li, K.; Veres, T.

2008-04-01

This work demonstrates the fabrication of metallic nanoprism (triangular nanostructure) arrays using a low-cost and high-throughput process. In the method, the triangular structure is defined by the shadow of a pyramid during angle evaporation of a metal etching mask. The pyramids were created by nanoimprint lithography in polymethylmethacrylate (PMMA) using a mould having an inverse-pyramid-shaped hole array formed by KOH wet etching of silicon. Silver and gold nanoprism arrays with a period of 200 nm and an edge length of 100 nm have been fabricated and used as effective substrates for surface enhanced Raman spectroscopy (SERS) detection of rhodamine 6G (R6G) molecules. Numerical calculations confirmed the great enhancement of electric field near the sharp nanoprism corners, as well as the detrimental effect of the chromium adhesion layer on localized surface plasmon resonance. The current method can also be used to fabricate non-equilateral nanoprism and three-dimensional (3D) nanopyramid arrays, and it can be readily extended to other metals.

Fabrication of large area nanoprism arrays and their application for surface enhanced Raman spectroscopy.

PubMed

Cui, B; Clime, L; Li, K; Veres, T

2008-04-09

This work demonstrates the fabrication of metallic nanoprism (triangular nanostructure) arrays using a low-cost and high-throughput process. In the method, the triangular structure is defined by the shadow of a pyramid during angle evaporation of a metal etching mask. The pyramids were created by nanoimprint lithography in polymethylmethacrylate (PMMA) using a mould having an inverse-pyramid-shaped hole array formed by KOH wet etching of silicon. Silver and gold nanoprism arrays with a period of 200 nm and an edge length of 100 nm have been fabricated and used as effective substrates for surface enhanced Raman spectroscopy (SERS) detection of rhodamine 6G (R6G) molecules. Numerical calculations confirmed the great enhancement of electric field near the sharp nanoprism corners, as well as the detrimental effect of the chromium adhesion layer on localized surface plasmon resonance. The current method can also be used to fabricate non-equilateral nanoprism and three-dimensional (3D) nanopyramid arrays, and it can be readily extended to other metals.

Template-Stripped Tunable Plasmonic Devices on Stretchable and Rollable Substrates

PubMed Central

2015-01-01

We use template stripping to integrate metallic nanostructures onto flexible, stretchable, and rollable substrates. Using this approach, high-quality patterned metals that are replicated from reusable silicon templates can be directly transferred to polydimethylsiloxane (PDMS) substrates. First we produce stretchable gold nanohole arrays and show that their optical transmission spectra can be modulated by mechanical stretching. Next we fabricate stretchable arrays of gold pyramids and demonstrate a modulation of the wavelength of light resonantly scattered from the tip of the pyramid by stretching the underlying PDMS film. The use of a flexible transfer layer also enables template stripping using a cylindrical roller as a substrate. As an example, we demonstrate roller template stripping of metallic nanoholes, nanodisks, wires, and pyramids onto the cylindrical surface of a glass rod lens. These nonplanar metallic structures produced via template stripping with flexible and stretchable films can facilitate many applications in sensing, display, plasmonics, metasurfaces, and roll-to-roll fabrication. PMID:26402066

Target-specific expression of presynaptic NMDA receptors in neocortical microcircuits.

PubMed

Buchanan, Katherine A; Blackman, Arne V; Moreau, Alexandre W; Elgar, Dale; Costa, Rui P; Lalanne, Txomin; Tudor Jones, Adam A; Oyrer, Julia; Sjöström, P Jesper

2012-08-09

Traditionally, NMDA receptors are located postsynaptically; yet, putatively presynaptic NMDA receptors (preNMDARs) have been reported. Although implicated in controlling synaptic plasticity, their function is not well understood and their expression patterns are debated. We demonstrate that, in layer 5 of developing mouse visual cortex, preNMDARs specifically control synaptic transmission at pyramidal cell inputs to other pyramidal cells and to Martinotti cells, while leaving those to basket cells unaffected. We also reveal a type of interneuron that mediates ascending inhibition. In agreement with synapse-specific expression, we find preNMDAR-mediated calcium signals in a subset of pyramidal cell terminals. A tuned network model predicts that preNMDARs specifically reroute information flow in local circuits during high-frequency firing, in particular by impacting frequency-dependent disynaptic inhibition mediated by Martinotti cells, a finding that we experimentally verify. We conclude that postsynaptic cell type determines presynaptic terminal molecular identity and that preNMDARs govern information processing in neocortical columns. Copyright © 2012 Elsevier Inc. All rights reserved.

Hyperconnectivity of local neocortical microcircuitry induced by prenatal exposure to valproic acid.

PubMed

Rinaldi, Tania; Silberberg, Gilad; Markram, Henry

2008-04-01

Exposure to valproic acid (VPA) during embryogenesis can cause several teratogenic effects, including developmental delays and in particular autism in humans if exposure occurs during the third week of gestation. We examined the postnatal effects of embryonic exposure to VPA on microcircuit properties of juvenile rat neocortex using in vitro electrophysiology. We found that a single prenatal injection of VPA on embryonic day 11.5 causes a significant enhancement of the local recurrent connectivity formed by neocortical pyramidal neurons. The study of the biophysical properties of these connections revealed weaker excitatory synaptic responses. A marked decrease of the intrinsic excitability of pyramidal neurons was also observed. Furthermore, we demonstrate a diminished number of putative synaptic contacts in connection between layer 5 pyramidal neurons. Local hyperconnectivity may render cortical modules more sensitive to stimulation and once activated, more autonomous, isolated, and more difficult to command. This could underlie some of the core symptoms observed in humans prenatally exposed to valproic acid.

Hyperconnectivity and slow synapses during early development of medial prefrontal cortex in a mouse model for mental retardation and autism.

PubMed

Testa-Silva, Guilherme; Loebel, Alex; Giugliano, Michele; de Kock, Christiaan P J; Mansvelder, Huibert D; Meredith, Rhiannon M

2012-06-01

Neuronal theories of neurodevelopmental disorders (NDDs) of autism and mental retardation propose that abnormal connectivity underlies deficits in attentional processing. We tested this theory by studying unitary synaptic connections between layer 5 pyramidal neurons within medial prefrontal cortex (mPFC) networks in the Fmr1-KO mouse model for mental retardation and autism. In line with predictions from neurocognitive theory, we found that neighboring pyramidal neurons were hyperconnected during a critical period in early mPFC development. Surprisingly, excitatory synaptic connections between Fmr1-KO pyramidal neurons were significantly slower and failed to recover from short-term depression as quickly as wild type (WT) synapses. By 4-5 weeks of mPFC development, connectivity rates were identical for both KO and WT pyramidal neurons and synapse dynamics changed from depressing to facilitating responses with similar properties in both groups. We propose that the early alteration in connectivity and synaptic recovery are tightly linked: using a network model, we show that slower synapses are essential to counterbalance hyperconnectivity in order to maintain a dynamic range of excitatory activity. However, the slow synaptic time constants induce decreased responsiveness to low-frequency stimulation, which may explain deficits in integration and early information processing in attentional neuronal networks in NDDs.

Hyperconnectivity and Slow Synapses during Early Development of Medial Prefrontal Cortex in a Mouse Model for Mental Retardation and Autism

PubMed Central

Testa-Silva, Guilherme; Loebel, Alex; Giugliano, Michele; de Kock, Christiaan P.J.; Mansvelder, Huibert D.; Meredith, Rhiannon M.

2013-01-01

Neuronal theories of neurodevelopmental disorders (NDDs) of autism and mental retardation propose that abnormal connectivity underlies deficits in attentional processing. We tested this theory by studying unitary synaptic connections between layer 5 pyramidal neurons within medial prefrontal cortex (mPFC) networks in the Fmr1-KO mouse model for mental retardation and autism. In line with predictions from neurocognitive theory, we found that neighboring pyramidal neurons were hyperconnected during a critical period in early mPFC development. Surprisingly, excitatory synaptic connections between Fmr1-KO pyramidal neurons were significantly slower and failed to recover from short-term depression as quickly as wild type (WT) synapses. By 4--5 weeks of mPFC development, connectivity rates were identical for both KO and WT pyramidal neurons and synapse dynamics changed from depressing to facilitating responses with similar properties in both groups. We propose that the early alteration in connectivity and synaptic recovery are tightly linked: using a network model, we show that slower synapses are essential to counterbalance hyperconnectivity in order to maintain a dynamic range of excitatory activity. However, the slow synaptic time constants induce decreased responsiveness to low-frequency stimulation, which may explain deficits in integration and early information processing in attentional neuronal networks in NDDs. PMID:21856714

Impaired inhibitory control of cortical synchronization in fragile X syndrome.

PubMed

Paluszkiewicz, Scott M; Olmos-Serrano, Jose Luis; Corbin, Joshua G; Huntsman, Molly M

2011-11-01

Fragile X syndrome (FXS) is a neurodevelopmental disorder characterized by severe cognitive impairments, sensory hypersensitivity, and comorbidities with autism and epilepsy. Fmr1 knockout (KO) mouse models of FXS exhibit alterations in excitatory and inhibitory neurotransmission, but it is largely unknown how aberrant function of specific neuronal subtypes contributes to these deficits. In this study we show specific inhibitory circuit dysfunction in layer II/III of somatosensory cortex of Fmr1 KO mice. We demonstrate reduced activation of somatostatin-expressing low-threshold-spiking (LTS) interneurons in response to the group I metabotropic glutamate receptor (mGluR) agonist 3,5-dihydroxyphenylglycine (DHPG) in Fmr1 KO mice, resulting in impaired synaptic inhibition. Paired recordings from pyramidal neurons revealed reductions in synchronized synaptic inhibition and coordinated spike synchrony in response to DHPG, indicating a weakened LTS interneuron network in Fmr1 KO mice. Together, these findings reveal a functional defect in a single subtype of cortical interneuron in Fmr1 KO mice. This defect is linked to altered activity of the cortical network in line with the FXS phenotype.

Reduction in spontaneous firing of mouse excitatory layer 4 cortical neurons following visual classical conditioning

NASA Astrophysics Data System (ADS)

Bekisz, Marek; Shendye, Ninad; Raciborska, Ida; Wróbel, Andrzej; Waleszczyk, Wioletta J.

2017-08-01

The process of learning induces plastic changes in neuronal network of the brain. Our earlier studies on mice showed that classical conditioning in which monocular visual stimulation was paired with an electric shock to the tail enhanced GABA immunoreactivity within layer 4 of the monocular part of the primary visual cortex (V1), contralaterally to the stimulated eye. In the present experiment we investigated whether the same classical conditioning paradigm induces changes of neuronal excitability in this cortical area. Two experimental groups were used: mice that underwent 7-day visual classical conditioning and controls. Patch-clamp whole-cell recordings were performed from ex vivo slices of mouse V1. The slices were perfused with the modified artificial cerebrospinal fluid, the composition of which better mimics the brain interstitial fluid in situ and induces spontaneous activity. The neuronal excitability was characterized by measuring the frequency of spontaneous action potentials. We found that layer 4 star pyramidal cells located in the monocular representation of the "trained" eye in V1 had lower frequency of spontaneous activity in comparison with neurons from the same cortical region of control animals. Weaker spontaneous firing indicates decreased general excitability of star pyramidal neurons within layer 4 of the monocular representation of the "trained" eye in V1. Such effect could result from enhanced inhibitory processes accompanying learning in this cortical area.

FGF-2 induces behavioral recovery after early adolescent injury to the motor cortex of rats.

PubMed

Nemati, Farshad; Kolb, Bryan

2011-11-20

Motor cortex injuries in adulthood lead to poor performance in behavioral tasks sensitive to limb movements in the rat. We have shown previously that motor cortex injury on day 10 or day 55 allow significant spontaneous recovery but not injury in early adolescence (postnatal day 35 "P35"). Previous studies have indicated that injection of basic fibroblast growth factor (FGF-2) enhances behavioral recovery after neonatal cortical injury but such effect has not been studied following motor cortex lesions in early adolescence. The present study undertook to investigate the possibility of such behavioral recovery. Rats with unilateral motor cortex lesions were assigned to two groups in which they received FGF-2 or bovine serum albumin (BSA) and were tested in a number of behavioral tests (postural asymmetry, skilled reaching, sunflower seed manipulation, forepaw inhibition in swimming). Golgi-Cox analysis was used to examine the dendritic structure of pyramidal cells in the animals' parietal (layer III) and forelimb (layer V) area of the cortex. The results indicated that rats injected with FGF-2 (but not BSA) showed significant behavioral recovery that was associated with increased dendritic length and spine density. The present study suggests a role for FGF-2 in the recovery of function following injury during early adolescence. Copyright © 2011 Elsevier B.V. All rights reserved.

Group I-III-VI.sub.2 semiconductor films for solar cell application

DOEpatents

Basol, Bulent M.; Kapur, Vijay K.

1991-01-01

This invention relates to an improved thin film solar cell with excellent electrical and mechanical integrity. The device comprises a substrate, a Group I-III-VI.sub.2 semiconductor absorber layer and a transparent window layer. The mechanical bond between the substrate and the Group I-III-VI.sub.2 semiconductor layer is enhanced by an intermediate layer between the substrate and the Group I-III-VI.sub.2 semiconductor film being grown. The intermediate layer contains tellurium or substitutes therefor, such as Se, Sn, or Pb. The intermediate layer improves the morphology and electrical characteristics of the Group I-III-VI.sub.2 semiconductor layer.

"Brief Report: Increase in Production of Spoken Words in Some Children with Autism after PECS Teaching to Phase III"

ERIC Educational Resources Information Center

Carr, Deborah; Felce, Janet

2007-01-01

The context for this work was an evaluation study [Carr, D., & Felce, J. A. (in press)] of the early phases of the Picture Exchange Communication System (PECS) [Frost, L. A., & Bondy, A. S. (1994). "The picture exchange communication system training manual." Cherry Hill, NJ: Pyramid Educational Consultants, Inc.; Frost, L. A., & Bondy, A. S.…

Dendritic mechanisms underlying the coupling of the dendritic with the axonal action potential initiation zone of adult rat layer 5 pyramidal neurons

PubMed Central

Larkum, M E; Zhu, J J; Sakmann, B

2001-01-01

Double, triple and quadruple whole-cell voltage recordings were made simultaneously from different parts of the apical dendritic arbor and the soma of adult layer 5 (L5) pyramidal neurons. We investigated the membrane mechanisms that support the conduction of dendritic action potentials (APs) between the dendritic and axonal AP initiation zones and their influence on the subsequent AP pattern. The duration of the current injection to the distal dendritic initiation zone controlled the degree of coupling with the axonal initiation zone and the AP pattern. Two components of the distally evoked regenerative potential were pharmacologically distinguished: a rapidly rising peak potential that was TTX sensitive and a slowly rising plateau-like potential that was Cd2+ and Ni2+ sensitive and present only with longer-duration current injection. The amplitude of the faster forward-propagating Na+-dependent component and the amplitude of the back-propagating AP fell into two classes (more distinctly in the forward-propagating case). Current injection into the dendrite altered propagation in both directions. Somatic current injections that elicited single Na+ APs evoked bursts of Na+ APs when current was injected simultaneously into the proximal apical dendrite. The mechanism did not depend on dendritic Na+–Ca2+ APs. A three-compartment model of a L5 pyramidal neuron is proposed. It comprises the distal dendritic and axonal AP initiation zones and the proximal apical dendrite. Each compartment contributes to the initiation and to the pattern of AP discharge in a distinct manner. Input to the three main dendritic arbors (tuft dendrites, apical oblique dendrites and basal dendrites) has a dominant influence on only one of these compartments. Thus, the AP pattern of L5 pyramids reflects the laminar distribution of synaptic activity in a cortical column. PMID:11389204

A New Layered Model on Emotional Intelligence

PubMed Central

Drigas, Athanasios S.

2018-01-01

Emotional Intelligence (EI) has been an important and controversial topic during the last few decades. Its significance and its correlation with many domains of life has made it the subject of expert study. EI is the rudder for feeling, thinking, learning, problem-solving, and decision-making. In this article, we present an emotional–cognitive based approach to the process of gaining emotional intelligence and thus, we suggest a nine-layer pyramid of emotional intelligence and the gradual development to reach the top of EI. PMID:29724021

A New Layered Model on Emotional Intelligence.

PubMed

Drigas, Athanasios S; Papoutsi, Chara

2018-05-02

Emotional Intelligence (EI) has been an important and controversial topic during the last few decades. Its significance and its correlation with many domains of life has made it the subject of expert study. EI is the rudder for feeling, thinking, learning, problem-solving, and decision-making. In this article, we present an emotional⁻cognitive based approach to the process of gaining emotional intelligence and thus, we suggest a nine-layer pyramid of emotional intelligence and the gradual development to reach the top of EI.

Cortical compression rapidly trimmed transcallosal projections and altered axonal anterograde transport machinery.

PubMed

Chen, Li-Jin; Wang, Yueh-Jan; Tseng, Guo-Fang

2017-10-24

Trauma and tumor compressing the brain distort underlying cortical neurons. Compressed cortical neurons remodel their dendrites instantly. The effects on axons however remain unclear. Using a rat epidural bead implantation model, we studied the effects of unilateral somatosensory cortical compression on its transcallosal projection and the reversibility of the changes following decompression. Compression reduced the density, branching profuseness and boutons of the projection axons in the contralateral homotopic cortex 1week and 1month post-compression. Projection fiber density was higher 1-month than 1-week post-compression, suggesting adaptive temporal changes. Compression reduced contralateral cortical synaptophysin, vesicular glutamate transporter 1 (VGLUT1) and postsynaptic density protein-95 (PSD95) expressions in a week and the first two marker proteins further by 1month. βIII-tubulin and kinesin light chain (KLC) expressions in the corpus callosum (CC) where transcallosal axons traveled were also decreased. Kinesin heavy chain (KHC) level in CC was temporarily increased 1week after compression. Decompression increased transcallosal axon density and branching profuseness to higher than sham while bouton density returned to sham levels. This was accompanied by restoration of synaptophysin, VGLUT1 and PSD95 expressions in the contralateral cortex of the 1-week, but not the 1-month, compression rats. Decompression restored βIII-tubulin, but not KLC and KHC expressions in CC. However, KLC and KHC expressions in the cell bodies of the layer II/III pyramidal neurons partially recovered. Our results show cerebral compression compromised cortical axonal outputs and reduced transcallosal projection. Some of these changes did not recover in long-term decompression. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Label-free multiphoton microscopy reveals altered tissue architecture in hippocampal sclerosis.

PubMed

Uckermann, Ortrud; Galli, Roberta; Leupold, Susann; Coras, Roland; Meinhardt, Matthias; Hallmeyer-Elgner, Susanne; Mayer, Thomas; Storch, Alexander; Schackert, Gabriele; Koch, Edmund; Blümcke, Ingmar; Steiner, Gerald; Kirsch, Matthias

2017-01-01

The properties and structure of tissue can be visualized without labeling or preparation by multiphoton microscopy combining coherent anti-Stokes Raman scattering (CARS), addressing lipid content, second harmonic generation (SHG) showing collagen, and two-photon excited fluorescence (TPEF) of endogenous fluorophores. We compared samples of sclerotic and nonsclerotic human hippocampus to detect pathologic changes in the brain of patients with pharmacoresistant temporomesial epilepsy (n = 15). Multiphoton microscopy of cryosections and bulk tissue revealed hippocampal layering and micromorphologic details in accordance with reference histology: CARS displayed white and gray matter layering and allowed the assessment of axonal myelin. SHG visualized blood vessels based on adventitial collagen. In addition, corpora amylacea (CoA) were found to be SHG-active. Pyramidal cell bodies were characterized by intense cytoplasmic endogenous TPEF. Furthermore, diffuse TPEF around blood vessels was observed that co-localized with positive albumin immunohistochemistry and might indicate degeneration-associated vascular leakage. We present a label-free and fast optical approach that analyzes pathologic aspects of HS. Hippocampal layering, loss of pyramidal cells, and presence of CoA indicative of sclerosis are visualized. Label-free multiphoton microscopy has the potential to extend the histopathologic armamentarium for ex vivo assessment of changes of the hippocampal formation on fresh tissue and prospectively in vivo. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

Layer- and cell-type-specific subthreshold and suprathreshold effects of long-term monocular deprivation in rat visual cortex.

PubMed

Medini, Paolo

2011-11-23

Connectivity and dendritic properties are determinants of plasticity that are layer and cell-type specific in the neocortex. However, the impact of experience-dependent plasticity at the level of synaptic inputs and spike outputs remains unclear along vertical cortical microcircuits. Here I compared subthreshold and suprathreshold sensitivity to prolonged monocular deprivation (MD) in rat binocular visual cortex in layer 4 and layer 2/3 pyramids (4Ps and 2/3Ps) and in thick-tufted and nontufted layer 5 pyramids (5TPs and 5NPs), which innervate different extracortical targets. In normal rats, 5TPs and 2/3Ps are the most binocular in terms of synaptic inputs, and 5NPs are the least. Spike responses of all 5TPs were highly binocular, whereas those of 2/3Ps were dominated by either the contralateral or ipsilateral eye. MD dramatically shifted the ocular preference of 2/3Ps and 4Ps, mostly by depressing deprived-eye inputs. Plasticity was profoundly different in layer 5. The subthreshold ocular preference shift was sevenfold smaller in 5TPs because of smaller depression of deprived inputs combined with a generalized loss of responsiveness, and was undetectable in 5NPs. Despite their modest ocular dominance change, spike responses of 5TPs consistently lost their typically high binocularity during MD. The comparison of MD effects on 2/3Ps and 5TPs, the main affected output cells of vertical microcircuits, indicated that subthreshold plasticity is not uniquely determined by the initial degree of input binocularity. The data raise the question of whether 5TPs are driven solely by 2/3Ps during MD. The different suprathreshold plasticity of the two cell populations could underlie distinct functional deficits in amblyopia.

Cytidine-5-diphosphocholine supplement in early life induces stable increase in dendritic complexity of neurons in the somatosensory cortex of adult rats

PubMed Central

Rema, V.; Bali, K.K.; Ramachandra, R.; Chugh, M.; Darokhan, Z.; Chaudhary, R.

2008-01-01

Cytidine-5-diphosphocholine (CDP-choline or citicholine) is an essential molecule that is required for biosynthesis of cell membranes. In adult humans it is used as a memory-enhancing drug for treatment of age-related dementia and cerebrovascular conditions. However the effect of CDP-choline on perinatal brain is not known. We administered CDP-choline to Long Evans rats each day from conception (maternal ingestion) to postnatal day 60 (P60). Pyramidal neurons from supragranular layers 2/3, granular layer 4 and infragranular layer 5 of somatosensory cortex were examined with Golgi–Cox staining at P240. CDP-choline treatment significantly increased length and branch points of apical and basal dendrites. Sholl analysis shows that the complexity of apical and basal dendrites of neurons is maximal in layers 2/3 and layer 5. In layer 4 significant increases were seen in basilar dendritic arborization. CDP-choline did not increase the number of primary basal dendrites on neurons in the somatosensory cortex. Primary cultures from somatosensory cortex were treated with CDP-choline to test its effect on neuronal survival. CDP-choline treatment neither enhanced the survival of neurons in culture nor increased the number of neurites. However significant increases in neurite length, branch points and total area occupied by the neurons were observed. We conclude that exogenous supplementation of CDP-choline during development causes stable changes in neuronal morphology. Significant increase in dendritic growth and branching of pyramidal neurons from the somatosensory cortex resulted in enlarging the surface area occupied by the neurons which we speculate will augment processing of sensory information. PMID:18619738

Distinct Roles of NMDAR and mGluR5 in Light Exposure Reversal of Feedforward Synaptic Strength in V1 of Juvenile Mice after Binocular Vision Deprivation.

PubMed

Tie, Xiaoxiu; Li, Shuo; Feng, Yilin; Lai, Biqin; Liu, Sheng; Jiang, Bin

2018-06-01

In the visual cortex, sensory deprivation causes global augmentation of the amplitude of AMPA receptor-mediated miniature EPSCs in layer 2/3 pyramidal cells and enhancement of NMDA receptor-dependent long-term potentiation (LTP) in cells activated in layer 4, effects that are both rapidly reversed by light exposure. Layer 2/3 pyramidal cells receive both feedforward input from layer 4 and intra-cortical lateral input from the same layer, LTP is mainly induced by the former input. Whether feedforward excitatory synaptic strength is affected by visual deprivation and light exposure, how this synaptic strength correlates with the magnitude of LTP in this pathway, and the underlying mechanism have not been explored. Here, we showed that in juvenile mice, both dark rearing and dark exposure reduced the feedforward excitatory synaptic strength, and the effects can be reversed completely by 10-12 h and 6-8 h light exposure, respectively. However, inhibition of NMDA receptors by CPP or mGluR5 by MPEP, prevented the effect of light exposure on the mice reared in the dark from birth, while only inhibition of NMDAR prevented the effect of light exposure on dark-exposed mice. These results suggested that the activation of both NMDAR and mGluR5 are essential in the light exposure reversal of feedforward excitatory synaptic strength in the dark reared mice from birth; while in the dark exposed mice, only activation of NMDAR is required. Copyright © 2018. Published by Elsevier Ltd.

Parvalbumin and calbindin immunoreactivity in the cerebral cortex of the hedgehog (Erinaceus europaeus).

PubMed Central

Ferrer, I; Zujar, M J; Admella, C; Alcantara, S

1992-01-01

To investigate the morphology and distribution of nonpyramidal neurons in the brain of insectivores, parvalbumin and calbindin 28 kDa immunoreactivity was examined in the cerebral cortex of the hedgehog (Erinaceus europaeus). Parvalbumin-immunoreactive cells were found in all layers of the isocortex, but in contrast to other mammals, a laminar organisation or specific regional distribution was not seen. Characteristic parvalbumin-immunoreactive neurons were multipolar cells with large ascending and descending dendrites extending throughout several layers. Calbindin-immunoreactive neurons were similar to those found in other species, although appearing in smaller numbers than in the cerebral cortex of more advanced mammals. The morphology and distribution of parvalbumin- and calbindin-immunoreactive cells in the piriform and entorhinal cortices were similar in hedgehogs and rodents. Parvalbumin-immunoreactive cells in the hippocampal complex were pyramidal-like and bitufted neurons, which were mainly found in the stratum oriens and stratum pyramidale of the hippocampus, and in the stratum moleculare and hilus of the fascia dentata. Heavily stained cells were found in the deep part of the stratum granulare. Intense calbindin immunoreactivity occurred mainly in the granule cell and molecular layers of the dentate gyrus and in the mossy fibre layer. The most outstanding feature in the hippocampal complex of the hedgehog was the extension of calbindin immunoreactivity to CA1 field of the hippocampus, suggesting, in agreement with other reports, that mossy fibres can establish synaptic contacts throughout the pyramidal cell layer. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:1452472

Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada

NASA Astrophysics Data System (ADS)

Eisses, A.; Kell, A. M.; Kent, G.; Driscoll, N. W.; Karlin, R. E.; Baskin, R. L.; Louie, J. N.; Smith, K. D.; Pullammanappallil, S.

2011-12-01

Preliminary slip rates measured across the East Pyramid Lake fault, or the Lake Range fault, help provide new estimates of extension across the Pyramid Lake basin. Multiple stratigraphic horizons spanning 48 ka were tracked throughout the lake, with layer offsets measured across all significant faults in the basin. A chronstratigraphic framework acquired from four sediment cores allows slip rates of the Lake Range and other faults to be calculated accurately. This region of the northern Walker Lake, strategically placed between the right-lateral strike-slip faults of Honey and Eagle Lakes to the north, and the normal fault bounded basins to the southwest (e.g., Tahoe, Carson), is critical in understanding the underlying structural complexity that is not only necessary for geothermal exploration, but also earthquake hazard assessment due to the proximity of the Reno-Sparks metropolitan area. In addition, our seismic CHIRP imaging with submeter resolution allows the construction of the first fault map of Pyramid Lake. The Lake Range fault can be obviously traced west of Anahoe Island extending north along the east end of the lake in numerous CHIRP lines. Initial drafts of the fault map reveal active transtension through a series of numerous, small, northwest striking, oblique-slip faults in the north end of the lake. A previously field mapped northwest striking fault near Sutcliff can be extended into the west end of Pyramid Lake. This fault map, along with the calculated slip rate of the Lake Range, and potentially multiple other faults, gives a clearer picture into understanding the geothermal potential, tectonic regime and earthquake hazards in the Pyramid Lake basin and the northern Walker Lane. These new results have also been merged with seismicity maps, along with focal mechanisms for the larger events to begin to extend our fault map in depth.

Using Social Studies Themes to Investigate Modern Egypt

ERIC Educational Resources Information Center

Hubbard, Janie

2010-01-01

Many elementary teachers explore the marvels of ancient Egypt with their students, as evidenced by the numerous available websites on this topic for teaching elementary history. The drama and mystery of ancient civilizations with treasures such as mummies, King Tut, and the Giza Pyramids are intriguing to children, yet there is another layer of…

Tie Points Extraction for SAR Images Based on Differential Constraints

NASA Astrophysics Data System (ADS)

Xiong, X.; Jin, G.; Xu, Q.; Zhang, H.

2018-04-01

Automatically extracting tie points (TPs) on large-size synthetic aperture radar (SAR) images is still challenging because the efficiency and correct ratio of the image matching need to be improved. This paper proposes an automatic TPs extraction method based on differential constraints for large-size SAR images obtained from approximately parallel tracks, between which the relative geometric distortions are small in azimuth direction and large in range direction. Image pyramids are built firstly, and then corresponding layers of pyramids are matched from the top to the bottom. In the process, the similarity is measured by the normalized cross correlation (NCC) algorithm, which is calculated from a rectangular window with the long side parallel to the azimuth direction. False matches are removed by the differential constrained random sample consensus (DC-RANSAC) algorithm, which appends strong constraints in azimuth direction and weak constraints in range direction. Matching points in the lower pyramid images are predicted with the local bilinear transformation model in range direction. Experiments performed on ENVISAT ASAR and Chinese airborne SAR images validated the efficiency, correct ratio and accuracy of the proposed method.

Hypergravity exposure decreases gamma-aminobutyric acid immunoreactivity in axon terminals contacting pyramidal cells in the rat somatosensory cortex: a quantitative immunocytochemical image analysis

NASA Technical Reports Server (NTRS)

D'Amelio, F.; Wu, L. C.; Fox, R. A.; Daunton, N. G.; Corcoran, M. L.; Polyakov, I.

1998-01-01

Quantitative evaluation of gamma-aminobutyric acid immunoreactivity (GABA-IR) in the hindlimb representation of the rat somatosensory cortex after 14 days of exposure to hypergravity (hyper-G) was conducted by using computer-assisted image processing. The area of GABA-IR axosomatic terminals apposed to pyramidal cells of cortical layer V was reduced in rats exposed to hyper-G compared with control rats, which were exposed either to rotation alone or to vivarium conditions. Based on previous immunocytochemical and behavioral studies, we suggest that this reduction is due to changes in sensory feedback information from muscle receptors. Consequently, priorities for muscle recruitment are altered at the cortical level, and a new pattern of muscle activity is thus generated. It is proposed that the reduction observed in GABA-IR of the terminal area around pyramidal neurons is the immunocytochemical expression of changes in the activity of GABAergic cells that participate in reprogramming motor outputs to achieve effective movement control in response to alterations in the afferent information.

GABAergic Neuron-Specific Loss of Ube3a Causes Angelman Syndrome-Like EEG Abnormalities and Enhances Seizure Susceptibility.

PubMed

Judson, Matthew C; Wallace, Michael L; Sidorov, Michael S; Burette, Alain C; Gu, Bin; van Woerden, Geeske M; King, Ian F; Han, Ji Eun; Zylka, Mark J; Elgersma, Ype; Weinberg, Richard J; Philpot, Benjamin D

2016-04-06

Loss of maternal UBE3A causes Angelman syndrome (AS), a neurodevelopmental disorder associated with severe epilepsy. We previously implicated GABAergic deficits onto layer (L) 2/3 pyramidal neurons in the pathogenesis of neocortical hyperexcitability, and perhaps epilepsy, in AS model mice. Here we investigate consequences of selective Ube3a loss from either GABAergic or glutamatergic neurons, focusing on the development of hyperexcitability within L2/3 neocortex and in broader circuit and behavioral contexts. We find that GABAergic Ube3a loss causes AS-like increases in neocortical EEG delta power, enhances seizure susceptibility, and leads to presynaptic accumulation of clathrin-coated vesicles (CCVs)-all without decreasing GABAergic inhibition onto L2/3 pyramidal neurons. Conversely, glutamatergic Ube3a loss fails to yield EEG abnormalities, seizures, or associated CCV phenotypes, despite impairing tonic inhibition onto L2/3 pyramidal neurons. These results substantiate GABAergic Ube3a loss as the principal cause of circuit hyperexcitability in AS mice, lending insight into ictogenic mechanisms in AS. Copyright © 2016 Elsevier Inc. All rights reserved.

GABAergic neuron-specific loss of Ube3a causes Angelman syndrome-like EEG abnormalities and enhances seizure susceptibility

PubMed Central

Judson, Matthew C.; Wallace, Michael L.; Sidorov, Michael S.; Burette, Alain C.; Gu, Bin; van Woerden, Geeske M.; King, Ian F.; Han, Ji Eun; Zylka, Mark J.; Elgersma, Ype; Weinberg, Richard J.; Philpot, Benjamin D.

2016-01-01

SUMMARY Loss of maternal UBE3A causes Angelman syndrome (AS), a neurodevelopmental disorder associated with severe epilepsy. We previously implicated GABAergic deficits onto layer (L) 2/3 pyramidal neurons in the pathogenesis of neocortical hyperexcitability, and perhaps epilepsy, in AS model mice. Here we investigate consequences of selective Ube3a loss from either GABAergic or glutamatergic neurons, focusing on the development of hyperexcitability within L2/3 neocortex and in broader circuit and behavioral contexts. We find that GABAergic Ube3a loss causes AS-like increases in neocortical EEG delta power, enhances seizure susceptibility, and leads to presynaptic accumulation of clathrin-coated vesicles (CCVs) – all without decreasing GABAergic inhibition onto L2/3 pyramidal neurons. Conversely, glutamatergic Ube3a loss fails to yield EEG abnormalities, seizures, or associated CCV phenotypes, despite impairing tonic inhibition onto L2/3 pyramidal neurons. These results substantiate GABAergic Ube3a loss as the principal cause of circuit hyperexcitability in AS mice, lending insight into ictogenic mechanisms in AS. PMID:27021170

Broadening the absorption bandwidth of metamaterial absorbers by transverse magnetic harmonics of 210 mode.

PubMed

Long, Chang; Yin, Sheng; Wang, Wei; Li, Wei; Zhu, Jianfei; Guan, Jianguo

2016-02-18

By investigating a square-shaped metamaterial structure we discover that wave diffraction at diagonal corners of such a structure excites transverse magnetic harmonics of 210 mode (TM210 harmonics). Multi-layer overlapping and deliberately regulating period length between adjacent unit cells can significantly enhance TM210 harmonics, leading to a strong absorption waveband. On such a basis, a design strategy is proposed to achieve broadband, thin-thickness multi-layered metamaterial absorbers (MMAs). In this strategy big pyramidal arrays placed in the "white blanks" of a chessboard exhibit two isolated absorption bands due to their fundamental and TM210 harmonics, which are further connected by another absorption band from small pyramidal arrays in the "black blanks" of the chessboard. The as-designed MMA at a total thickness (h) of 4.36 mm shows an absorption of above 0.9 in the whole frequency range of 7-18 GHz, which is 38% broader with respect to previous design methods at the same h. This strategy provides an effective route to extend the absorption bandwidth of MMAs without increasing h.

Impact of substrate off-angle on the m-plane GaN Schottky diodes

NASA Astrophysics Data System (ADS)

Yamada, Hisashi; Chonan, Hiroshi; Takahashi, Tokio; Shimizu, Mitsuaki

2018-04-01

We investigated the effects of the substrate off-angle on the m-plane GaN Schottky diodes. GaN epitaxial layers were grown by metal-organic chemical vapor deposition on m-plane GaN substrates having an off-angle of 0.1, 1.1, 1.7, or 5.1° toward [000\\bar{1}]. The surface of the GaN epitaxial layers on the 0.1°-off substrate consisted of pyramidal hillocks and contained oxygen (>1017 cm-3) and carbon (>1016 cm-3) impurities. The residual carbon and oxygen impurities decreased to <1016 cm-3 when the off-angle of the m-plane GaN substrate was increased. The leakage current of the 0.1°-off m-plane GaN Schottky diodes originated from the +c facet of the pyramidal hillocks. The leakage current was efficiently suppressed through the use of an off-angle that was observed to be greater than 1.1°. The off-angle of the m-plane GaN substrate is critical in obtaining high-performance Schottky diodes.

Preserving the Pyramid of STI Using Buckets

NASA Technical Reports Server (NTRS)

Nelson, Michael L.; Maly, Kurt

2004-01-01

The product of research projects is information. Through the life cycle of a project, information comes from many sources and takes many forms. Traditionally, this body of information is summarized in a formal publication, typically a journal article. While formal publications enjoy the benefits of peer review and technical editing, they are also often compromises in media format and length. As such, we consider a formal publication to represent an abstract to a larger body of work: a pyramid of scientific and technical information (STI). While this abstract may be sufficient for some applications, an in-depth use or analysis is likely to require the supporting layers from the pyramid. We have developed buckets to preserve this pyramid of STI. Buckets provide an archive- and protocol-independent container construct in which all related information objects can be logically grouped together, archived, and manipulated as a single object. Furthermore, buckets are active archival objects and can communicate with each other, people, or arbitrary network services. Buckets are an implementation of the Smart Object, Dumb Archive (SODA) DL model. In SODA, data objects are more important than the archives that hold them. Much of the functionality traditionally associated with archives is pushed down into the objects, such as enforcing terms and conditions, negotiating display, and content maintenance. In this paper, we discuss the motivation, design, and implication of bucket use in DLs with respect to grey literature.

Calcium Dynamics in Basal Dendrites of Layer 5A and 5B Pyramidal Neurons Is Tuned to the Cell-Type Specific Physiological Action Potential Discharge

PubMed Central

Krieger, Patrik; de Kock, Christiaan P. J.; Frick, Andreas

2017-01-01

Layer 5 (L5) is a major neocortical output layer containing L5A slender-tufted (L5A-st) and L5B thick-tufted (L5B-tt) pyramidal neurons. These neuron types differ in their in vivo firing patterns, connectivity and dendritic morphology amongst other features, reflecting their specific functional role within the neocortical circuits. Here, we asked whether the active properties of the basal dendrites that receive the great majority of synaptic inputs within L5 differ between these two pyramidal neuron classes. To quantify their active properties, we measured the efficacy with which action potential (AP) firing patterns backpropagate along the basal dendrites by measuring the accompanying calcium transients using two-photon laser scanning microscopy in rat somatosensory cortex slices. For these measurements we used both “artificial” three-AP patterns and more complex physiological AP patterns that were previously recorded in anesthetized rats in L5A-st and L5B-tt neurons in response to whisker stimulation. We show that AP patterns with relatively few APs (3APs) evoke a calcium response in L5B-tt, but not L5A-st, that is dependent on the temporal pattern of the three APs. With more complex in vivo recorded AP patterns, the average calcium response was similar in the proximal dendrites but with a decay along dendrites (measured up to 100 μm) of L5B-tt but not L5A-st neurons. Interestingly however, the whisker evoked AP patterns—although very different for the two cell types—evoke similar calcium responses. In conclusion, although the effectiveness with which different AP patterns evoke calcium transients vary between L5A-st and L5B-tt cell, the calcium influx appears to be tuned such that whisker-evoked calcium transients are within the same dynamic range for both cell types. PMID:28744201

Axonal properties determine somatic firing in a model of in vitro CA1 hippocampal sharp wave/ripples and persistent gamma oscillations

PubMed Central

Traub, Roger D.; Schmitz, Dietmar; Maier, Nikolaus; Whittington, Miles A.; Draguhn, Andreas

2012-01-01

Evidence has been presented that CA1 pyramidal cells, during spontaneous in vitro sharp wave/ripple (SPW-R) complexes, generate somatic action potentials that originate in axons. ‘Participating’ (somatically firing) pyramidal cells fire (almost always) at most once during a particular SPW-R whereas non-participating cells virtually never fire during an SPW-R. Somatic spikelets were small or absent, while ripple-frequency EPSCs and IPSCs occurred during the SPW-R in pyramidal neurons. These experimental findings could be replicated with a network model in which electrical coupling was present between small pyramidal cell axonal branches. Here, we explore this model in more depth. Factors that influence somatic participation include: (i) the diameter of axonal branches that contain coupling sites to other axons, because firing in larger branches injects more current into the main axon, increasing antidromic firing probability; (ii) axonal K+ currents; and (iii) somatic hyperpolarization and shunting. We predict that portions of axons fire at high frequency during SPW-R, while somata fire much less. In the model, somatic firing can occur by occasional generation of full action potentials in proximal axonal branches, which are excited by high-frequency spikelets. When the network contains phasic synaptic inhibition, at the axonal gap junction site, gamma oscillations result, again with more frequent axonal firing than somatic firing. Combining the models, so as to generate gamma followed by sharp waves, leads to strong overlap between the population of cells firing during gamma the population of cells firing during a subsequent sharp wave, as observed in vivo. PMID:22697272

Evidence for encoding versus retrieval scheduling in the hippocampus by theta phase and acetylcholine

PubMed Central

Douchamps, Vincent; Jeewajee, Ali; Blundell, Pam; Burgess, Neil; Lever, Colin

2013-01-01

The formation of new memories requires new information to be encoded in the face of proactive interference from the past. Two solutions have been proposed for hippocampal region CA1: 1) acetylcholine, released in novelty, selectively suppresses excitatory projections to CA1 from CA3 (mediating the products of retrieval), while sparing entorhinal inputs (mediating novel sensory information); 2) encoding preferentially occurs at the pyramidal-layer theta peak, coincident with input from entorhinal cortex, and retrieval occurs at the trough, coincident with input from CA3, consistent with theta-phase-dependent synaptic plasticity. We examined three predictions of these models: 1) In novel environments, the preferred theta phase of CA1 place cell firing should shift closer to the CA1 pyramidal-layer theta peak, shifting the encoding-retrieval balance towards encoding; 2) The encoding-related shift in novel environments should be disrupted by cholinergic antagonism; 3) In familiar environments, cholinergic antagonism should shift the preferred theta firing phase closer to the theta trough, shifting the encoding-retrieval balance even further towards retrieval. We tested these predictions by recording from CA1 pyramidal cells in freely moving rats as they foraged in open field environments under the influence of scopolamine (an amnestic cholinergic antagonist) or vehicle (saline). Results confirmed all three predictions, supporting both the theta phase and cholinergic models of encoding-vs-retrieval dynamics. Also consistent with cholinergic enhancement of encoding, scopolamine attenuated the formation of distinct spatial representations in a new environment, reducing the extent of place cell “remapping”. PMID:23678113

Antibacterial activity and spectral studies of trivalent chromium, manganese, iron macrocyclic complexes derived from oxalyldihydrazide and glyoxal.

PubMed

Singh, D P; Kumar, Ramesh; Singh, Jitender

2009-06-01

A new series of complexes is synthesized by template condensation of oxalyldihydrazide and glyoxal in methanolic medium in the presence of trivalent chromium, manganese and iron salts forming complexes of the type: [M(C(8)H(8)N(8)O(4))X]X(2) where M = Cr(III), Mn(III), Fe(III) and X = Cl(-1), NO(-1)(3), CH(3)COO(-1). The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic susceptibility measurements, electronic, NMR, infrared and far infrared spectral studies. On the basis of these studies, a five coordinate square pyramidal geometry for these complexes has been proposed. The biological activities of the metal complexes were tested in vitro against a number of pathogenic bacteria and some of the complexes exhibited remarkable antibacterial activities.

A Novel Form of Compensation in the Tg2576 Amyloid Mouse Model of Alzheimer’s Disease

PubMed Central

Somogyi, Attila; Katonai, Zoltán; Alpár, Alán; Wolf, Ervin

2016-01-01

One century after its first description, pathology of Alzheimer’s disease (AD) is still poorly understood. Amyloid-related dendritic atrophy and membrane alterations of susceptible brain neurons in AD, and in animal models of AD are widely recognized. However, little effort has been made to study the potential effects of combined morphological and membrane alterations on signal transfer and synaptic integration in neurons that build up affected neural networks in AD. In this study spatial reconstructions and electrophysiological measurements of layer II/III pyramidal neurons of the somatosensory cortex from wild-type (WT) and transgenic (TG) human amyloid precursor protein (hAPP) overexpressing Tg2576 mice were used to build faithful segmental cable models of these neurons. Local synaptic activities were simulated in various points of the dendritic arbors and properties of subthreshold dendritic impulse propagation and predictors of synaptic input pattern recognition ability were quantified and compared in modeled WT and TG neurons. Despite the widespread dendritic degeneration and membrane alterations in mutant mouse neurons, surprisingly little, or no change was detected in steady-state and 50 Hz sinusoidal voltage transfers, current transfers, and local and propagation delays of PSPs traveling along dendrites of TG neurons. Synaptic input pattern recognition ability was also predicted to be unaltered in TG neurons in two different soma-dendritic membrane models investigated. Our simulations predict the way how subthreshold dendritic signaling and pattern recognition are preserved in TG neurons: amyloid-related membrane alterations compensate for the pathological effects that dendritic atrophy has on subthreshold dendritic signal transfer and integration in layer II/III somatosensory neurons of this hAPP mouse model for AD. Since neither propagation of single PSPs nor integration of multiple PSPs (pattern recognition) changes in TG neurons, we conclude that AD-related neuronal hyperexcitability cannot be accounted for by altered subthreshold dendritic signaling in these neurons but hyperexcitability is related to changes in active membrane properties and network connectivity. PMID:27378850

A Novel Form of Compensation in the Tg2576 Amyloid Mouse Model of Alzheimer's Disease.

PubMed

Somogyi, Attila; Katonai, Zoltán; Alpár, Alán; Wolf, Ervin

2016-01-01

One century after its first description, pathology of Alzheimer's disease (AD) is still poorly understood. Amyloid-related dendritic atrophy and membrane alterations of susceptible brain neurons in AD, and in animal models of AD are widely recognized. However, little effort has been made to study the potential effects of combined morphological and membrane alterations on signal transfer and synaptic integration in neurons that build up affected neural networks in AD. In this study spatial reconstructions and electrophysiological measurements of layer II/III pyramidal neurons of the somatosensory cortex from wild-type (WT) and transgenic (TG) human amyloid precursor protein (hAPP) overexpressing Tg2576 mice were used to build faithful segmental cable models of these neurons. Local synaptic activities were simulated in various points of the dendritic arbors and properties of subthreshold dendritic impulse propagation and predictors of synaptic input pattern recognition ability were quantified and compared in modeled WT and TG neurons. Despite the widespread dendritic degeneration and membrane alterations in mutant mouse neurons, surprisingly little, or no change was detected in steady-state and 50 Hz sinusoidal voltage transfers, current transfers, and local and propagation delays of PSPs traveling along dendrites of TG neurons. Synaptic input pattern recognition ability was also predicted to be unaltered in TG neurons in two different soma-dendritic membrane models investigated. Our simulations predict the way how subthreshold dendritic signaling and pattern recognition are preserved in TG neurons: amyloid-related membrane alterations compensate for the pathological effects that dendritic atrophy has on subthreshold dendritic signal transfer and integration in layer II/III somatosensory neurons of this hAPP mouse model for AD. Since neither propagation of single PSPs nor integration of multiple PSPs (pattern recognition) changes in TG neurons, we conclude that AD-related neuronal hyperexcitability cannot be accounted for by altered subthreshold dendritic signaling in these neurons but hyperexcitability is related to changes in active membrane properties and network connectivity.

III-nitride nanopyramid light emitting diodes grown by organometallic vapor phase epitaxy

NASA Astrophysics Data System (ADS)

Wildeson, Isaac H.; Colby, Robert; Ewoldt, David A.; Liang, Zhiwen; Zakharov, Dmitri N.; Zaluzec, Nestor J.; García, R. Edwin; Stach, Eric A.; Sands, Timothy D.

2010-08-01

Nanopyramid light emitting diodes (LEDs) have been synthesized by selective area organometallic vapor phase epitaxy. Self-organized porous anodic alumina is used to pattern the dielectric growth templates via reactive ion etching, eliminating the need for lithographic processes. (In,Ga)N quantum well growth occurs primarily on the six {11¯01} semipolar facets of each of the nanopyramids, while coherent (In,Ga)N quantum dots with heights of up to ˜20 nm are incorporated at the apex by controlling growth conditions. Transmission electron microscopy (TEM) indicates that the (In,Ga)N active regions of the nanopyramid heterostructures are completely dislocation-free. Temperature-dependent continuous-wave photoluminescence of nanopyramid heterostructures yields a peak emission wavelength of 617 nm and 605 nm at 300 K and 4 K, respectively. The peak emission energy varies with increasing temperature with a double S-shaped profile, which is attributed to either the presence of two types of InN-rich features within the nanopyramids or a contribution from the commonly observed yellow defect luminescence close to 300 K. TEM cross-sections reveal continuous planar defects in the (In,Ga)N quantum wells and GaN cladding layers grown at 650-780 °C, present in 38% of the nanopyramid heterostructures. Plan-view TEM of the planar defects confirms that these defects do not terminate within the nanopyramids. During the growth of p-GaN, the structure of the nanopyramid LEDs changed from pyramidal to a partially coalesced film as the thickness requirements for an undepleted p-GaN layer result in nanopyramid impingement. Continuous-wave electroluminescence of nanopyramid LEDs reveals a 45 nm redshift in comparison to a thin-film LED, suggesting higher InN incorporation in the nanopyramid LEDs. These results strongly encourage future investigations of III-nitride nanoheteroepitaxy as an approach for creating efficient long wavelength LEDs.

Translations on Narcotics and Dangerous Drugs, Number 279

DTIC Science & Technology

1977-01-06

III - INT - 138] CONTENTS (Continued) Page LATIN AMERICA BOLIVIA Bolivia Seen as Base of Drug Pyramid ( PRESENCIA ,, 12 Nov 76) 12 Plans To...governments of those countries. It was not elected and it has full power in making decisive economic and social decisions and implementing them quickly. An...La Paz PRESENCIA in Spanish 12 Nov 76 p 9 PY [Text] Roberto Valda said yesterday during a lecture that Bolivia, as a cocaine producing country, was

Dorsoventral differences in Kv7/M-current and its impact on resonance, temporal summation and excitability in rat hippocampal pyramidal cells

PubMed Central

Hönigsperger, Christoph; Marosi, Máté; Murphy, Ricardo; Storm, Johan F

2015-01-01

Key points Kv7 (KCNQ/M) channels are known to control excitability and generate subthreshold M-resonance in CA1 hippocampal pyramidal cells, but their properties and functions have not previously been compared along the dorsoventral (septotemporal) axis We used whole-cell recordings to compare electrophysiological properties of dorsal and ventral CA1 pyramidal cells in hippocampal slices from 3- to 4-week-old rats Blockade of Kv7/M-channels with 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone dihydrochloride (XE991) had a stronger impact on electrical properties in dorsal than ventral pyramidal cells, including input resistance, temporal summation, M-resonance, spike threshold, medium after-hyperpolarization, excitability, and spike frequency adaptation. Voltage-clamp recordings revealed a larger amplitude and left-shifted voltage dependence of XE991-sensitive current (IM) in dorsal vs. ventral cells. IM-dependent differences in excitability and resonance may be important for rate and phase coding of CA1 place cells along the dorsoventral axis and may enhance epileptiform activity in ventral pyramidal cells. Abstract In rodent hippocampi, the connections, gene expression and functions differ along the dorsoventral (D–V) axis. CA1 pyramidal cells show increasing excitability along the D–V axis, although the underlying mechanism is not known. In the present study, we investigated how the M-current (IM), caused by Kv7/M (KCNQ) potassium channels, and known to often control neuronal excitability, contributes to D–V differences in intrinsic properties of CA1 pyramidal cells. Using whole-cell patch clamp recordings and the selective Kv7/M blocker 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone dihydrochloride (XE991) in hippocampal slices from 3- to 4-week-old rats, we found that: (i) IM had a stronger impact on subthreshold electrical properties in dorsal than ventral CA1 pyramidal cells, including input resistance, temporal summation of artificial synaptic potentials, and M-resonance; (ii) IM activated at more negative potentials (left-shifted) and had larger peak amplitude in the dorsal than ventral CA1; and (iii) the initial spike threshold (during ramp depolarizations) was elevated, and the medium after-hyperpolarization and spike frequency adaptation were increased (i.e. excitability was lower) in the dorsal rather than ventral CA1. These differences were abolished or reduced by application of XE991, indicating that they were caused by IM. Thus, it appears that IM has stronger effects in dorsal than in ventral rat CA1 pyramidal cells because of a larger maximal M-conductance and left-shifted activation curve in the dorsal cells. These mechanisms may contribute to D–V differences in the rate and phase coding of position by CA1 place cells, and may also enhance epileptiform activity in ventral CA1. PMID:25656084

Temperature-dependent evolution of the wetting layer thickness during Ge deposition on Si(001).

PubMed

Bergamaschini, R; Brehm, M; Grydlik, M; Fromherz, T; Bauer, G; Montalenti, F

2011-07-15

The evolution of the wetting layer (WL) thickness during Ge deposition on Si(001) is analyzed with the help of a rate-equation approach. The combined role of thickness, island volume and shape-dependent chemical potentials is considered. Several experimental observations, such as WL thinning following the pyramid-to-dome transformation, are captured by the model, as directly demonstrated by a close comparison with photoluminescence measurements (PL) on samples grown at three different temperatures. The limitations of the model in describing late stages of growth are critically addressed.

Syntheses, structures, and magnetic properties of a family of heterometallic heptanuclear [Cu5Ln2] (Ln = Y(III), Lu(III), Dy(III), Ho(III), Er(III), and Yb(III)) complexes: observation of SMM behavior for the Dy(III) and Ho(III) analogues.

PubMed

Chandrasekhar, Vadapalli; Dey, Atanu; Das, Sourav; Rouzières, Mathieu; Clérac, Rodolphe

2013-03-04

Sequential reaction of the multisite coordination ligand (LH3) with Cu(OAc)2·H2O, followed by the addition of a rare-earth(III) nitrate salt in the presence of triethylamine, afforded a series of heterometallic heptanuclear complexes containing a [Cu5Ln2] core {Ln = Y(1), Lu(2), Dy(3), Ho(4), Er(5), and Yb(6)}. Single-crystal X-ray crystallography reveals that all the complexes are dicationic species that crystallize with two nitrate anions to compensate the charge. The heptanuclear aggregates in 1-6 are centrosymmetrical complexes, with a hexagonal-like arrangement of six peripheral metal ions (two rare-earth and four copper) around a central Cu(II) situated on a crystallographic inversion center. An all-oxygen environment is found to be present around the rare-earth metal ions, which adopt a distorted square-antiprismatic geometry. Three different Cu(II) sites are present in the heptanuclear complexes: two possess a distorted octahedral coordination sphere while the remaining one displays a distorted square-pyramidal geometry. Detailed static and dynamic magnetic properties of all the complexes have been studied and revealed the single-molecule magnet behavior of the Dy(III) and Ho(III) derivatives.

Methods for improved growth of group III nitride buffer layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melnik, Yurity; Chen, Lu; Kojiri, Hidehiro

Methods are disclosed for growing high crystal quality group III-nitride epitaxial layers with advanced multiple buffer layer techniques. In an embodiment, a method includes forming group III-nitride buffer layers that contain aluminum on suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. A hydrogen halide or halogen gas is flowing into the growth zone during deposition of buffer layers to suppress homogeneous particle formation. Some combinations of low temperature buffers that contain aluminum (e.g., AlN, AlGaN) and high temperature buffers that contain aluminum (e.g., AlN, AlGaN) may be used to improve crystal quality and morphologymore » of subsequently grown group III-nitride epitaxial layers. The buffer may be deposited on the substrate, or on the surface of another buffer. The additional buffer layers may be added as interlayers in group III-nitride layers (e.g., GaN, AlGaN, AlN).« less

Glutamate-Bound NMDARs Arising from In Vivo-like Network Activity Extend Spatio-temporal Integration in a L5 Cortical Pyramidal Cell Model

PubMed Central

Farinella, Matteo; Ruedt, Daniel T.; Gleeson, Padraig; Lanore, Frederic; Silver, R. Angus

2014-01-01

In vivo, cortical pyramidal cells are bombarded by asynchronous synaptic input arising from ongoing network activity. However, little is known about how such ‘background’ synaptic input interacts with nonlinear dendritic mechanisms. We have modified an existing model of a layer 5 (L5) pyramidal cell to explore how dendritic integration in the apical dendritic tuft could be altered by the levels of network activity observed in vivo. Here we show that asynchronous background excitatory input increases neuronal gain and extends both temporal and spatial integration of stimulus-evoked synaptic input onto the dendritic tuft. Addition of fast and slow inhibitory synaptic conductances, with properties similar to those from dendritic targeting interneurons, that provided a ‘balanced’ background configuration, partially counteracted these effects, suggesting that inhibition can tune spatio-temporal integration in the tuft. Excitatory background input lowered the threshold for NMDA receptor-mediated dendritic spikes, extended their duration and increased the probability of additional regenerative events occurring in neighbouring branches. These effects were also observed in a passive model where all the non-synaptic voltage-gated conductances were removed. Our results show that glutamate-bound NMDA receptors arising from ongoing network activity can provide a powerful spatially distributed nonlinear dendritic conductance. This may enable L5 pyramidal cells to change their integrative properties as a function of local network activity, potentially allowing both clustered and spatially distributed synaptic inputs to be integrated over extended timescales. PMID:24763087

Low-spin manganese(II) and high-spin manganese(III) complexes derived from disalicylaldehyde oxaloyldihydrazone: Synthesis, spectral characterization and electrochemical studies

NASA Astrophysics Data System (ADS)

Syiemlieh, Ibanphylla; Kumar, Arvind; Kurbah, Sunshine D.; De, Arjune K.; Lal, Ram A.

2018-01-01

Low-spin manganese(II) complexes [MnII(H2slox)].H2O (1), [MnII(H2slox)(SL)] (where SL (secondary ligand) = pyridine (py, 2), 2-picoline (2-pic, 3), 3-picoline (3-pic, 4), and 4-picoline (4-pic, 5) and high-spin manganese(III) complex Na(H2O)4[MnIII(slox)(H2O)2].2.5H2O have been synthesized from disalicyaldehyde oxaloyldihydrazone in methanolic - water medium. The composition of complexes has been established by elemental analyses and thermoanalytical data. The structures of the complexes have been discussed on the basis of data obtained from molar conductance, UV visible, 1H NMR, infrared spectra, magnetic moment and electron paramagnetic resonance spectroscopic studies. Conductivity measurements in DMF suggest that the complexes (1-5) are non-electrolyte while the complex (6) is 1:1 electrolyte. The electronic spectral studies and magnetic moment data suggest five - coordinate square pyramidal structure for the complexes (2-5) and square planar geometry for manganese(II) in complex (1). In complex (6), both sodium and manganese(III) have six coordinate octahedral geometry. IR spectral studies reveal that the dihydrazone coordinates to the manganese centre in keto form in complexes (1-5) and in enol form in complex (6). In all complexes, the ligand is present in anti-cis configuration. Magnetic moment and EPR studies indicate manganese in +2 oxidation state in complexes (1-5), with low-spin square planar complex (1) and square pyramidal stereochemistries complexes (2-5) while in +3 oxidation state in high-spin distorted octahedral stereochemistry in complex (6). The complex (1) involves significant metal - metal interaction in the solid state. All of the complexes show only one metal centred electron transfer reaction in DMF solution in cyclic voltammetric studies. The complexes (1-5) involve MnII→MnI redox reaction while the complex (6) involves MnIII→MnII redox reaction, respectively.

Increased transient Na+ conductance and action potential output in layer 2/3 prefrontal cortex neurons of the fmr1-/y mouse.

PubMed

Routh, Brandy N; Rathour, Rahul K; Baumgardner, Michael E; Kalmbach, Brian E; Johnston, Daniel; Brager, Darrin H

2017-07-01

Layer 2/3 neurons of the prefrontal cortex display higher gain of somatic excitability, responding with a higher number of action potentials for a given stimulus, in fmr1 -/y mice. In fmr1 -/y L2/3 neurons, action potentials are taller, faster and narrower. Outside-out patch clamp recordings revealed that the maximum Na + conductance density is higher in fmr1 -/y L2/3 neurons. Measurements of three biophysically distinct K + currents revealed a depolarizing shift in the activation of a rapidly inactivating (A-type) K + conductance. Realistic neuronal simulations of the biophysical observations recapitulated the elevated action potential and repetitive firing phenotype. Fragile X syndrome is the most common form of inherited mental impairment and autism. The prefrontal cortex is responsible for higher order cognitive processing, and prefrontal dysfunction is believed to underlie many of the cognitive and behavioural phenotypes associated with fragile X syndrome. We recently demonstrated that somatic and dendritic excitability of layer (L) 5 pyramidal neurons in the prefrontal cortex of the fmr1 -/y mouse is significantly altered due to changes in several voltage-gated ion channels. In addition to L5 pyramidal neurons, L2/3 pyramidal neurons play an important role in prefrontal circuitry, integrating inputs from both lower brain regions and the contralateral cortex. Using whole-cell current clamp recording, we found that L2/3 pyramidal neurons in prefrontal cortex of fmr1 -/y mouse fired more action potentials for a given stimulus compared with wild-type neurons. In addition, action potentials in fmr1 -/y neurons were significantly larger, faster and narrower. Voltage clamp of outside-out patches from L2/3 neurons revealed that the transient Na + current was significantly larger in fmr1 -/y neurons. Furthermore, the activation curve of somatic A-type K + current was depolarized. Realistic conductance-based simulations revealed that these biophysical changes in Na + and K + channel function could reliably reproduce the observed increase in action potential firing and altered action potential waveform. These results, in conjunction with our prior findings on L5 neurons, suggest that principal neurons in the circuitry of the medial prefrontal cortex are altered in distinct ways in the fmr1 -/y mouse and may contribute to dysfunctional prefrontal cortex processing in fragile X syndrome. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl: A rare example of Ti(IV) in a square pyramidal oxygen coordination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batuk, Maria, E-mail: Maria.Batuk@uantwerpen.be; Batuk, Dmitry; Abakumov, Artem M.

A new oxychloride Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl has been synthesized using the solid state method. Its crystal and magnetic structure was investigated in the 1.5–550 K temperature range using electron diffraction, high angle annular dark field scanning transmission electron microscopy, atomic resolution energy dispersive X-ray spectroscopy, neutron and X-ray powder diffraction. At room temperature Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl crystallizes in the P4/mmm space group with the unit cell parameters a=3.91803(3) Å and c=19.3345(2) Å. Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl is a new n=4 member of the oxychloride perovskite-based homologous series A{sub n+1}B{sub n}O{sub 3n−1}Cl. The structure is built of truncated Pb{submore » 3}Fe{sub 3}TiO{sub 11} quadruple perovskite blocks separated by CsCl-type Pb{sub 2}Cl slabs. The perovskite blocks consist of two layers of (Fe,Ti)O{sub 6} octahedra sandwiched between two layers of (Fe,Ti)O{sub 5} square pyramids. The Ti{sup 4+} cations are preferentially located in the octahedral layers, however, the presence of a noticeable amount of Ti{sup 4+} in a five-fold coordination environment has been undoubtedly proven using neutron powder diffraction and atomic resolution compositional mapping. Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl is antiferromagnetically ordered below 450(10) K. The ordered Fe magnetic moments at 1.5 K are 4.06(4) μ{sub B} and 3.86(5) μ{sub B} on the octahedral and square-pyramidal sites, respectively. - Highlights: • Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl has been synthesized using the solid state method. • The structure has been refined using neutron powder diffraction data at 1.5–550 K. • It is a new n=4 member of the perovskite-related homologous series A{sub n+1}B{sub n}O{sub 3n−1}Cl. • Ti{sup 4+} cations have both octahedral and square-pyramidal coordination environment. • Pb{sub 5}Fe{sub 3}TiO{sub 11}Cl is antiferromagnetically ordered below T{sub N}≈450 K.« less

Silicide formation process of Er films with Ta and TaN capping layers.

PubMed

Choi, Juyun; Choi, Seongheum; Kim, Jungwoo; Na, Sekwon; Lee, Hoo-Jeong; Lee, Seok-Hee; Kim, Hyoungsub

2013-12-11

The phase development and defect formation during the silicidation reaction of sputter-deposited Er films on Si with ∼20-nm-thick Ta and TaN capping layers were examined. TaN capping effectively prevented the oxygen incorporation from the annealing atmosphere, which resulted in complete conversion to the ErSi2-x phase. However, significant oxygen penetration through the Ta capping layer inhibited the ErSi2-x formation, and incurred the growth of several Er-Si-O phases, even consuming the ErSi2-x layer formed earlier. Both samples produced a number of small recessed defects at an early silicidation stage. However, large rectangular or square-shaped surface defects, which were either pitlike or pyramidal depending on the capping layer identity, were developed as the annealing temperature increased. The origin of different defect generation mechanisms was suggested based on the capping layer-dependent silicidation kinetics.

Excitatory and inhibitory synaptic connectivity to layer V fast-spiking interneurons in the freeze lesion model of cortical microgyria

PubMed Central

Jin, Xiaoming; Jiang, Kewen

2014-01-01

A variety of major developmental cortical malformations are closely associated with clinically intractable epilepsy. Pathophysiological aspects of one such disorder, human polymicrogyria, can be modeled by making neocortical freeze lesions (FL) in neonatal rodents, resulting in the formation of microgyri. Previous studies showed enhanced excitatory and inhibitory synaptic transmission and connectivity in cortical layer V pyramidal neurons in the paramicrogyral cortex. In young adult transgenic mice that express green fluorescent protein (GFP) specifically in parvalbumin positive fast-spiking (FS) interneurons, we used laser scanning photostimulation (LSPS) of caged glutamate to map excitatory and inhibitory synaptic connectivity onto FS interneurons in layer V of paramicrogyral cortex in control and FL groups. The proportion of uncaging sites from which excitatory postsynaptic currents (EPSCs) could be evoked (hotspot ratio) increased slightly but significantly in FS cells of the FL vs. control cortex, while the mean amplitude of LSPS-evoked EPSCs at hotspots did not change. In contrast, the hotspot ratio of inhibitory postsynaptic currents (IPSCs) was significantly decreased in FS neurons of the FL cortex. These alterations in synaptic inputs onto FS interneurons may result in an enhanced inhibitory output. We conclude that alterations in synaptic connectivity to cortical layer V FS interneurons do not contribute to hyperexcitability of the FL model. Instead, the enhanced inhibitory output from these neurons may partially offset an earlier demonstrated increase in synaptic excitation of pyramidal cells and thereby maintain a relative balance between excitation and inhibition in the affected cortical circuitry. PMID:24990567

How do neurons work together? Lessons from auditory cortex.

PubMed

Harris, Kenneth D; Bartho, Peter; Chadderton, Paul; Curto, Carina; de la Rocha, Jaime; Hollender, Liad; Itskov, Vladimir; Luczak, Artur; Marguet, Stephan L; Renart, Alfonso; Sakata, Shuzo

2011-01-01

Recordings of single neurons have yielded great insights into the way acoustic stimuli are represented in auditory cortex. However, any one neuron functions as part of a population whose combined activity underlies cortical information processing. Here we review some results obtained by recording simultaneously from auditory cortical populations and individual morphologically identified neurons, in urethane-anesthetized and unanesthetized passively listening rats. Auditory cortical populations produced structured activity patterns both in response to acoustic stimuli, and spontaneously without sensory input. Population spike time patterns were broadly conserved across multiple sensory stimuli and spontaneous events, exhibiting a generally conserved sequential organization lasting approximately 100 ms. Both spontaneous and evoked events exhibited sparse, spatially localized activity in layer 2/3 pyramidal cells, and densely distributed activity in larger layer 5 pyramidal cells and putative interneurons. Laminar propagation differed however, with spontaneous activity spreading upward from deep layers and slowly across columns, but sensory responses initiating in presumptive thalamorecipient layers, spreading rapidly across columns. In both unanesthetized and urethanized rats, global activity fluctuated between "desynchronized" state characterized by low amplitude, high-frequency local field potentials and a "synchronized" state of larger, lower-frequency waves. Computational studies suggested that responses could be predicted by a simple dynamical system model fitted to the spontaneous activity immediately preceding stimulus presentation. Fitting this model to the data yielded a nonlinear self-exciting system model in synchronized states and an approximately linear system in desynchronized states. We comment on the significance of these results for auditory cortical processing of acoustic and non-acoustic information. © 2010 Elsevier B.V. All rights reserved.

Neurons of human nucleus accumbens.

PubMed

Sazdanović, Maja; Sazdanović, Predrag; Zivanović-Macuzić, Ivana; Jakovljević, Vladimir; Jeremić, Dejan; Peljto, Amir; Tosevski, Jovo

2011-08-01

Nucleus accumbens is a part of the ventral striatum also known as a drug active brain region, especially related with drug addiction. The aim of the study was to investigate the Golgi morphology of the nucleus accumbens neurons. The study was performed on the frontal and sagittal sections of 15 human brains by the Golgi Kopsch method. We classified neurons in the human nucleus accumbens according to their morphology and size into four types: type I--fusiform neurons; type II--fusiform neurons with lateral dendrite, arising from a part of the cell body; type III--pyramidal-like neuron; type IV--multipolar neuron. The medium spiny neurons, which are mostly noted regarding to the drug addictive conditions of the brain, correspond to the type IV--multipolar neurons. Two regions of human nucleus accumbens could be clearly recognized on Nissl and Golgi preparations each containing different predominant neuronal types. Central part of nucleus accumbens, core region, has a low density of impregnated neurons with predominant type III, pyramidal-like neurons, with spines on secondary branches and rare type IV, multipolar neurons. Contrary to the core, peripheral region, shell of nucleus, has a high density of impregnated neurons predominantly contained of type I and type IV--multipolar neurons, which all are rich in spines on secondary and tertiary dendritic branches. Our results indicate great morphological variability of human nucleus accumbens neurons. This requires further investigations and clarifying clinical significance of this important brain region.

Mechanisms underlying subunit independence in pyramidal neuron dendrites

PubMed Central

Behabadi, Bardia F.; Mel, Bartlett W.

2014-01-01

Pyramidal neuron (PN) dendrites compartmentalize voltage signals and can generate local spikes, which has led to the proposal that their dendrites act as independent computational subunits within a multilayered processing scheme. However, when a PN is strongly activated, back-propagating action potentials (bAPs) sweeping outward from the soma synchronize dendritic membrane potentials many times per second. How PN dendrites maintain the independence of their voltage-dependent computations, despite these repeated voltage resets, remains unknown. Using a detailed compartmental model of a layer 5 PN, and an improved method for quantifying subunit independence that incorporates a more accurate model of dendritic integration, we first established that the output of each dendrite can be almost perfectly predicted by the intensity and spatial configuration of its own synaptic inputs, and is nearly invariant to the rate of bAP-mediated “cross-talk” from other dendrites over a 100-fold range. Then, through an analysis of conductance, voltage, and current waveforms within the model cell, we identify three biophysical mechanisms that together help make independent dendritic computation possible in a firing neuron, suggesting that a major subtype of neocortical neuron has been optimized for layered, compartmentalized processing under in-vivo–like spiking conditions. PMID:24357611

An Augmented Two-Layer Model Captures Nonlinear Analog Spatial Integration Effects in Pyramidal Neuron Dendrites.

PubMed

Jadi, Monika P; Behabadi, Bardia F; Poleg-Polsky, Alon; Schiller, Jackie; Mel, Bartlett W

2014-05-01

In pursuit of the goal to understand and eventually reproduce the diverse functions of the brain, a key challenge lies in reverse engineering the peculiar biology-based "technology" that underlies the brain's remarkable ability to process and store information. The basic building block of the nervous system is the nerve cell, or "neuron," yet after more than 100 years of neurophysiological study and 60 years of modeling, the information processing functions of individual neurons, and the parameters that allow them to engage in so many different types of computation (sensory, motor, mnemonic, executive, etc.) remain poorly understood. In this paper, we review both historical and recent findings that have led to our current understanding of the analog spatial processing capabilities of dendrites, the major input structures of neurons, with a focus on the principal cell type of the neocortex and hippocampus, the pyramidal neuron (PN). We encapsulate our current understanding of PN dendritic integration in an abstract layered model whose spatially sensitive branch-subunits compute multidimensional sigmoidal functions. Unlike the 1-D sigmoids found in conventional neural network models, multidimensional sigmoids allow the cell to implement a rich spectrum of nonlinear modulation effects directly within their dendritic trees.

Synthesis, spectroscopic, and antibacterial activity of tetraazamacrocyclic complexes of trivalent chromium, manganese, and iron.

PubMed

Singh, D P; Malik, Vandna; Kumar, Ramesh; Singh, Jitender

2009-10-01

A new series of macrocyclic complexes of type [M(TML)X]X(2), where M = Cr(III), Mn(III), or Fe(III), TML is tetradentate macrocyclic ligand, and X = Cl(-), NO(3)(-), CH(3)COO(-) for Cr(III), Fe(III) and X = CH(3)COO(-) for Mn (III), has been synthesized by condensation of benzil and succinyldihydrazide in the presence of metal salt. The complexes have been so formulated due to the 1:2 electrolytic nature of these complexes as shown by conductivity measurements. The complexes have been characterized with the help of various physicochemical techniques such as elemental analysis, molar conductance, electronic and infrared spectral studies, and magnetic susceptibility. On the basis of these studies, a five-coordinate distorted square pyramidal geometry, in which two nitrogens and two carbonyl oxygen atoms are suitably placed for coordination toward the metal ion, has been proposed for all the complexes. The complexes have been tested for their in vitro antibacterial activity. Some of the complexes show remarkable antibacterial activities against some selected bacterial strains. The minimum inhibitory concentrations shown by these complexes have been compared with those shown by some standard antibiotics such as linezolid and cefaclor.

Dendritic Arborization and Spine Dynamics Are Abnormal in the Mouse Model of MECP2 Duplication Syndrome

PubMed Central

Jiang, Minghui; Ash, Ryan T.; Baker, Steven A.; Suter, Bernhard; Ferguson, Andrew; Park, Jiyoung; Rudy, Jessica; Torsky, Sergey P.; Chao, Hsiao-Tuan; Zoghbi, Huda Y.

2013-01-01

MECP2 duplication syndrome is a childhood neurological disorder characterized by intellectual disability, autism, motor abnormalities, and epilepsy. The disorder is caused by duplications spanning the gene encoding methyl-CpG-binding protein-2 (MeCP2), a protein involved in the modulation of chromatin and gene expression. MeCP2 is thought to play a role in maintaining the structural integrity of neuronal circuits. Loss of MeCP2 function causes Rett syndrome and results in abnormal dendritic spine morphology and decreased pyramidal dendritic arbor complexity and spine density. The consequences of MeCP2 overexpression on dendritic pathophysiology remain unclear. We used in vivo two-photon microscopy to characterize layer 5 pyramidal neuron spine turnover and dendritic arborization as a function of age in transgenic mice expressing the human MECP2 gene at twice the normal levels of MeCP2 (Tg1; Collins et al., 2004). We found that spine density in terminal dendritic branches is initially higher in young Tg1 mice but falls below control levels after postnatal week 12, approximately correlating with the onset of behavioral symptoms. Spontaneous spine turnover rates remain high in older Tg1 animals compared with controls, reflecting the persistence of an immature state. Both spine gain and loss rates are higher, with a net bias in favor of spine elimination. Apical dendritic arbors in both simple- and complex-tufted layer 5 Tg1 pyramidal neurons have more branches of higher order, indicating that MeCP2 overexpression induces dendritic overgrowth. P70S6K was hyperphosphorylated in Tg1 somatosensory cortex, suggesting that elevated mTOR signaling may underlie the observed increase in spine turnover and dendritic growth. PMID:24336718

Graphene oxide-Ag nanoparticles-pyramidal silicon hybrid system for homogeneous, long-term stable and sensitive SERS activity

NASA Astrophysics Data System (ADS)

Guo, Jia; Xu, Shicai; Liu, Xiaoyun; Li, Zhe; Hu, Litao; Li, Zhen; Chen, Peixi; Ma, Yong; Jiang, Shouzhen; Ning, Tingyin

2017-02-01

In our work, few layers graphene oxide (GO) were directly synthesized on Ag nanoparticles (AgNPs) by spin-coating method to fabricate a GO-AgNPs hybrid structure on a pyramidal silicon (PSi) substrate for surface-enhanced Raman scattering (SERS). The GO-AgNPs-PSi substrate showed excellent Raman enhancement effect, the minimum detected concentration for Rhodamine 6G (R6G) can reach 10-12 M, which is one order of magnitude lower than the AgNPs-PSi substrate and two order of magnitude lower than the GO-AgNPs-flat-Si substrate. The linear fit calibration curve with error bars is presented and the value of R2 of 612 and 773 cm-1 can reach 0.986 and 0.980, respectively. The excellent linear response between the Raman intensity and R6G concentrations prove that the prepared GO-AgNPs-PSi substrates can serve as good SERS substrate for molecule detection. The maximum deviations of SERS intensities from 20 positions of the GO-AgNPs-PSi substrate are less than 8%, revealing the high homogeneity of the SERS substrate. The excellent homogeneity of the enhanced Raman signals can be attributed to well-separated pyramid arrays of PSi, the uniform morphology of AgNPs and multi-functions of GO layer. Besides, the uniform GO film can effectively protect AgNPs from oxidation and endow the hybrid system a good stability and long lifetime. This GO-AgNPs-PSi substrate may provide a new way toward practical applications for the ultrasensitive and label-free SERS detection in areas of medicine, food safety and biotechnology.

Vertical III-nitride thin-film power diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wierer, Jr., Jonathan; Fischer, Arthur J.; Allerman, Andrew A.

2017-03-14

A vertical III-nitride thin-film power diode can hold off high voltages (kV's) when operated under reverse bias. The III-nitride device layers can be grown on a wider bandgap template layer and growth substrate, which can be removed by laser lift-off of the epitaxial device layers grown thereon.

Bidirectional control of social hierarchy by synaptic efficacy in medial prefrontal cortex.

PubMed

Wang, Fei; Zhu, Jun; Zhu, Hong; Zhang, Qi; Lin, Zhanmin; Hu, Hailan

2011-11-04

Dominance hierarchy has a profound impact on animals' survival, health, and reproductive success, but its neural circuit mechanism is virtually unknown. We found that dominance ranking in mice is transitive, relatively stable, and highly correlates among multiple behavior measures. Recording from layer V pyramidal neurons of the medial prefrontal cortex (mPFC) showed higher strength of excitatory synaptic inputs in mice with higher ranking, as compared with their subordinate cage mates. Furthermore, molecular manipulations that resulted in an increase and decrease in the synaptic efficacy in dorsal mPFC neurons caused an upward and downward movement in the social rank, respectively. These results provide direct evidence for mPFC's involvement in social hierarchy and suggest that social rank is plastic and can be tuned by altering synaptic strength in mPFC pyramidal cells.

Fibronectin domains of extracellular matrix molecule tenascin-C modulate hippocampal learning and synaptic plasticity.

PubMed

Strekalova, Tatyana; Sun, Mu; Sibbe, Mirjam; Evers, Matthias; Dityatev, Alexander; Gass, Peter; Schachner, Melitta

2002-09-01

The extracellular matrix molecule tenascin-C (TN-C) has been shown to be involved in hippocampal synaptic plasticity in vitro. Here, we describe a deficit in hippocampus-dependent contextual memory in TN-C-deficient mice using the step-down avoidance paradigm. We further show that a fragment of TN-C containing the fibronectin type-III repeats 6-8 (FN6-8), but not a fragment containing repeats 3-5, bound to pyramidal and granule cell somata in the hippocampal formation of C57BL/6J mice and repelled axons of pyramidal neurons when presented as a border in vitro. Injection of the FN6-8 fragment into the hippocampus inhibited retention of memory in the step-down paradigm and reduced levels of long-term potentiation in the CA1 region of the hippocampus. In summary, our data show that TN-C is involved in hippocampus-dependent contextual memory and synaptic plasticity and identify the FN6-8 domain as one of molecular determinants mediating these functions.

Changes by short-term hypoxia in the membrane properties of pyramidal cells and the levels of purine and pyrimidine nucleotides in slices of rat neocortex; effects of agonists and antagonists of ATP-dependent potassium channels.

PubMed

Pissarek, M; Garcia de Arriba, S; Schäfer, M; Sieler, D; Nieber, K; Illes, P

1998-10-01

In a first series of experiments, intracellular recordings were made from pyramidal cells in layers II-III of the rat primary somatosensory cortex. Superfusion of the brain slice preparations with hypoxic medium (replacement of 95%O2-5%CO2 with 95%N2-5%CO2) for up to 30 min led to a time-dependent depolarization (HD) without a major change in input resistance. Short periods of hypoxia (5 min) induced reproducible depolarizations which were concentration-dependently depressed by an agonist of ATP-dependent potassium (K(ATP)) channels, diazoxide (3-300 microM). The effect of 30 but not 300 microM diazoxide was reversed by washout. Tolbutamide (300 microM), an antagonist of K(ATP) channels, did not alter the HD when given alone. It did, however, abolish the inhibitory effect of diazoxide (30 microM) on the HD. Neither diazoxide (3-300 microM) nor tolbutamide (300 microM) influenced the membrane potential or the apparent input resistance of the neocortical pyramidal cells. Current-voltage (I-V) curves constructed at a membrane potential of -90 mV by injecting both de- and hyperpolarizing current pulses were not altered by diazoxide (30 microM) or tolbutamide (300 microM). Moreover, normoxic and hypoxic I-V curves did not cross each other, excluding a reversal of the HD at any membrane potential between -130 and -50 mV. The hypoxia-induced change of the I-V relation was the same both in the absence and presence of tolbutamide (300 microM). In a second series of experiments, nucleoside di- and triphosphates separated with anion exchange HPLC were measured in the neocortical slices. After 5 min of hypoxia, levels of nucleoside triphosphates declined by 29% (GTP), 34% (ATP), 44% (UTP) and 58% (CTP). By contrast, the levels of nucleoside diphosphates either did not change (UDP) or increased by 13% (GDP) and 40% (ADP). In slices subjected to 30 min of hypoxia the triphosphate levels continued to decrease, while the levels of GDP and ADP returned to control values. The tri- to diphosphate ratios progressively declined for ATP/ADP and GTP/GDP, but not for UTP/UDP when the duration of hypoxia was increased from 5 to 30 min. Hence, the rapid fall in the ratios of nucleoside tri- to diphosphates without the induction of a potassium current failed to indicate an allosteric regulation of a plasmalemmal K(ATP) channel by purine and pyrimidine nucleotides. Diazoxide had no effect on neocortical pyramidal neurons and was effective only in combination with a hypoxic stimulus; it is suggested that both plasmalemmal and mitochondrial K(ATP) channels are involved under these conditions. The hypoxic depolarization may be due to blockade of K+,Na+-ATPase by limitation of energy supplying substrate.

2D Si island nucleation on the Si(111) surface at initial and late growth stages: On the role of step permeability in pyramidlike growth

NASA Astrophysics Data System (ADS)

Rogilo, D. I.; Fedina, L. I.; Kosolobov, S. S.; Ranguelov, B. S.; Latyshev, A. V.

2017-01-01

Initial and late stages of 2D Si island nucleation and growth (2DNG) on extra-large ( 100 μm) and medium size (1-10 μm) atomically flat Si(111)-(7×7) terraces bordered by step bunches have been studied by in situ REM at T =600-750 °С. At first, the layer-by-layer 2DNG takes place on whole terraces and 2D island concentration dependence on deposition rate R corresponds to critical nucleus size i =1. Continuous 2DNG triggers morphological instabilities: elongated pyramidlike waves and separate pyramids emerge on all terraces at T ≤720 °С and T =750 °С, respectively. Both instabilities arise due to the imbalance of uphill/downhill adatom currents related with large Ehrlich-Schwöbel (ES) barriers and permeability of straight [ 11 bar 2 ] -type step edges. However, the first one is initiated by dominant downhill adatom current to distant sinks: bunches, wave's step edges, and "vacancy" islands emerging on terraces due to 2D island coalescence. As a result, top layer size decreases to the critical terrace width λ where 2DNG takes place. From the analysis of λ ∝ R - χ / 2 scaling at T =650 °C, we have found that i increases from i =2 on a three-layer wave to i =6-8 on a six-layer wave. This authenticates the significance of downhill adatom sink to distant steps related to the step permeability. The second instability type at T >720 °C is related to the raising of uphill adatom current due to slightly larger ES barrier for step-up attachment comparing to the step-down one (EES- 0.9 eV [Phys. Rev. Lett. 111 (2013) 036105]). This leads to "second layer" 2D nucleation on top layers, which triggers the growth of separate pyramids. Because of small difference between ES barriers, net uphill/downhill adatom currents are nearly equivalent, and therefore layer coverage distributions of both instabilities display similar linear slopes.

Single-layer group IV-V and group V-IV-III-VI semiconductors: Structural stability, electronic structures, optical properties, and photocatalysis

NASA Astrophysics Data System (ADS)

Lin, Jia-He; Zhang, Hong; Cheng, Xin-Lu; Miyamoto, Yoshiyuki

2017-07-01

Recently, single-layer group III monochalcogenides have attracted both theoretical and experimental interest at their potential applications in photonic devices, electronic devices, and solar energy conversion. Excited by this, we theoretically design two kinds of highly stable single-layer group IV-V (IV =Si ,Ge , and Sn; V =N and P) and group V-IV-III-VI (IV =Si ,Ge , and Sn; V =N and P; III =Al ,Ga , and In; VI =O and S) compounds with the same structures with single-layer group III monochalcogenides via first-principles simulations. By using accurate hybrid functional and quasiparticle methods, we show the single-layer group IV-V and group V-IV-III-VI are indirect bandgap semiconductors with their bandgaps and band edge positions conforming to the criteria of photocatalysts for water splitting. By applying a biaxial strain on single-layer group IV-V, single-layer group IV nitrides show a potential on mechanical sensors due to their bandgaps showing an almost linear response for strain. Furthermore, our calculations show that both single-layer group IV-V and group V-IV-III-VI have absorption from the visible light region to far-ultraviolet region, especially for single-layer SiN-AlO and SnN-InO, which have strong absorption in the visible light region, resulting in excellent potential for solar energy conversion and visible light photocatalytic water splitting. Our research provides valuable insight for finding more potential functional two-dimensional semiconductors applied in optoelectronics, solar energy conversion, and photocatalytic water splitting.

Wetting layer effect on impurity-related electronic properties of different (In,Ga)N QD-shapes

NASA Astrophysics Data System (ADS)

El Ghazi, Haddou; Jorio, Anouar; Zorkani, Izeddine; Feddi, El Mustapha; El Mouchtachi, Ahmed

2018-05-01

In this paper, we have investigated the electronic properties of (In,Ga)N/GaN coupled wetting layer-quantum dot system using the numerical approach. The finite element method code is used to solve the Schrödinger equation, in the presence of the impurity. In our model, parallelepiped-shape, circular and square based-pyramidal and their wetting layers embedded in GaN matrix were considered. Based on the single band parabolic and the effective mass approximations, the envelop function and its corresponding energy eigenvalue are obtained assuming a finite potential barrier. Our results reveal that: (1) the wetting layer has a great influence on the electronic properties especially for a small quantum dot and acts in the opposite sense of the geometrical confinement, (2) a wetting layer-dependent critical QD-size is obtained limiting two different behaviors and (3) its effect is strongly-dependent on the quantum dot-shape.

Nucleation and Early Stages of Layer-by-Layer Growth of Metal Organic Frameworks on Surfaces

PubMed Central

2015-01-01

High resolution atomic force microscopy (AFM) is used to resolve the evolution of crystallites of a metal organic framework (HKUST-1) grown on Au(111) using a liquid-phase layer-by-layer methodology. The nucleation and faceting of individual crystallites is followed by repeatedly imaging the same submicron region after each cycle of growth and we find that the growing surface is terminated by {111} facets leading to the formation of pyramidal nanostructures for [100] oriented crystallites, and triangular [111] islands with typical lateral dimensions of tens of nanometres. AFM images reveal that crystallites can grow by 5–10 layers in each cycle. The growth rate depends on crystallographic orientation and the morphology of the gold substrate, and we demonstrate that under these conditions the growth is nanocrystalline with a morphology determined by the minimum energy surface. PMID:26709359

Seeing Our Way Clear: Feminist Revision of the Academy. Proceedings of the Annual GLCA Women's Studies Conference (8th, November 5-7, 1981).

ERIC Educational Resources Information Center

Loring, Katherine, Ed.; And Others

Two keynote addresses and 12 selected papers are included in these conference proceedings. The keynote address, "Seeing Our Way Clear: Feminist Re-Vision of the Academy" (Peggy McIntosh), describes the academy as a "hierarchical or layered pyramidal structure" and discusses the benefits of feminist revision. The first of 12…

Heterogeneous firing responses predict diverse couplings to presynaptic activity in mice layer V pyramidal neurons

PubMed Central

2017-01-01

In this study, we present a theoretical framework combining experimental characterizations and analytical calculus to capture the firing rate input-output properties of single neurons in the fluctuation-driven regime. Our framework consists of a two-step procedure to treat independently how the dendritic input translates into somatic fluctuation variables, and how the latter determine action potential firing. We use this framework to investigate the functional impact of the heterogeneity in firing responses found experimentally in young mice layer V pyramidal cells. We first design and calibrate in vitro a simplified morphological model of layer V pyramidal neurons with a dendritic tree following Rall's branching rule. Then, we propose an analytical derivation for the membrane potential fluctuations at the soma as a function of the properties of the synaptic input in dendrites. This mathematical description allows us to easily emulate various forms of synaptic input: either balanced, unbalanced, synchronized, purely proximal or purely distal synaptic activity. We find that those different forms of dendritic input activity lead to various impact on the somatic membrane potential fluctuations properties, thus raising the possibility that individual neurons will differentially couple to specific forms of activity as a result of their different firing response. We indeed found such a heterogeneous coupling between synaptic input and firing response for all types of presynaptic activity. This heterogeneity can be explained by different levels of cellular excitability in the case of the balanced, unbalanced, synchronized and purely distal activity. A notable exception appears for proximal dendritic inputs: increasing the input level can either promote firing response in some cells, or suppress it in some other cells whatever their individual excitability. This behavior can be explained by different sensitivities to the speed of the fluctuations, which was previously associated to different levels of sodium channel inactivation and density. Because local network connectivity rather targets proximal dendrites, our results suggest that this aspect of biophysical heterogeneity might be relevant to neocortical processing by controlling how individual neurons couple to local network activity. PMID:28410418

Transmitter release modulation by intracellular Ca2+ buffers in facilitating and depressing nerve terminals of pyramidal cells in layer 2/3 of the rat neocortex indicates a target cell-specific difference in presynaptic calcium dynamics

PubMed Central

Rozov, A; Burnashev, N; Sakmann, B; Neher, E

2001-01-01

In connections formed by nerve terminals of layer 2/3 pyramidal cells onto bitufted interneurones in young (postnatal day (P)14–15) rat somatosensory cortex, the efficacy and reliability of synaptic transmission were low. At these connections release was facilitated by paired-pulse stimulation (at 10 Hz). In connections formed by terminals of layer 2/3 pyramids with multipolar interneurones efficacy and reliability were high and release was depressed by paired-pulse stimulation. In both types of terminal, however, the voltage-dependent Ca2+ channels that controlled transmitter release were predominantly of the P/Q- and N-subtypes. The relationship between unitary EPSP amplitude and extracellular calcium concentration ([Ca2+]o) was steeper for facilitating than for depressing terminals. Fits to a Hill equation with nH= 4 indicated that the apparent KD of the Ca2+ sensor for vesicle release was two- to threefold lower in depressing terminals than in facilitating ones. Intracellular loading of pyramidal neurones with the fast and slowly acting Ca2+ buffers BAPTA and EGTA differentially reduced transmitter release in these two types of terminal. Unitary EPSPs evoked by pyramidal cell stimulation in bitufted cells were reduced by presynaptic BAPTA and EGTA with half-effective concentrations of ∼0.1 and ∼1 mm, respectively. Unitary EPSPs evoked in multipolar cells were reduced to one-half of control at higher concentrations of presynaptic BAPTA and EGTA (∼0.5 and ∼7 mm, respectively). Frequency-dependent facilitation of EPSPs in bitufted cells was abolished by EGTA at concentrations of > 0.2 mm, suggesting that accumulation of free Ca2+ is essential for facilitation in the terminals contacting bitufted cells. In contrast, facilitation was unaffected or even slightly increased in the terminals loaded with BAPTA in the concentration range 0.02–0.5 mm. This is attributed to partial saturation of exogenously added BAPTA. However, BAPTA at concentrations > 1 mm also abolished facilitation. Frequency-dependent depression of EPSPs in multipolar cells was not significantly reduced by EGTA. With BAPTA, the depression decreased at concentrations > 0.5 mm, concomitant with a reduction in amplitude of the first EPSP in a train. An analysis is presented that interprets the effects of EGTA and BAPTA on synaptic efficacy and its short-term modification during paired-pulse stimulation in terms of changes in [Ca2+] at the release site ([Ca2+]RS) and that infers the affinity of the Ca2+ sensor from the dependence of unitary EPSPs on [Ca2+]o. The results suggest that the target cell-specific difference in release from the terminals on bitufted or multipolar cells can be explained by a longer diffusional distance between Ca2+ channels and release sites and/or lower Ca2+ channels density in the terminals that contact bitufted cells. This would lead to a lower [Ca2+] at release sites and would also explain the higher apparent KD of the Ca2+ sensor in facilitating terminals. PMID:11251060

The response of L5 pyramidal neurons of the PFC to magnetic stimulation from a micro-coil.

PubMed

Lee, Seung Woo; Fried, Shelley I

2014-01-01

Magnetic stimulation of the nervous system, e.g. transcranial magnetic stimulation (TMS), has been used both to unravel basic structure and function of the nervous system as well as to treat neurological diseases, i.e. clinical depression. Despite progress in both areas, ongoing advancements have been limited by a lack of understanding of the mechanism by which magnetic stimulation alters neural activity. Here, we report responses of cortical neurons to magnetic stimulation arising from a sub-millimeter coil. Cell attached patch clamp was used to record neural activity of layer 5/6 pyramidal neurons of the prefrontal cortex (PFC) in the in vitro mouse brain slice preparation. The fields arising from the small coil were quite different from those arising during clinical TMS but nevertheless allowed the responses of cortical neurons to magnetic stimulation to be probed. For example, the focal nature of induced fields allowed the sensitivity of different regions within targeted pyramidal neurons, e.g. apical dendrite, soma and axon hillock, to be compared. We found that PFC pyramidal neurons were not sensitive to single pulses of stimulation regardless of coil location. However, regions of the apical dendrite and proximal axon were both sensitive to repetitive stimulation as long as the orientation of the induced electric field was aligned with the long axis of the neuron. These results suggest that neurons of the PFC are sensitive to weak magnetic fields and further, that this type of approach may be useful for unraveling some of the mechanisms underlying TMS.

Dynamics of action potential backpropagation in basal dendrites of prefrontal cortical pyramidal neurons.

PubMed

Zhou, Wen-Liang; Yan, Ping; Wuskell, Joseph P; Loew, Leslie M; Antic, Srdjan D

2008-02-01

Basal dendrites of neocortical pyramidal neurons are relatively short and directly attached to the cell body. This allows electrical signals arising in basal dendrites to strongly influence the neuronal output. Likewise, somatic action potentials (APs) should readily propagate back into the basilar dendritic tree to influence synaptic plasticity. Two recent studies, however, determined that sodium APs are severely attenuated in basal dendrites of cortical pyramidal cells, so that they completely fail in distal dendritic segments. Here we used the latest improvements in the voltage-sensitive dye imaging technique (Zhou et al., 2007) to study AP backpropagation in basal dendrites of layer 5 pyramidal neurons of the rat prefrontal cortex. With a signal-to-noise ratio of > 15 and minimal temporal averaging (only four sweeps) we were able to sample AP waveforms from the very last segments of individual dendritic branches (dendritic tips). We found that in short- (< 150 microm) and medium (150-200 microm in length)-range basal dendrites APs backpropagated with modest changes in AP half-width or AP rise-time. The lack of substantial changes in AP shape and dynamics of rise is inconsistent with the AP-failure model. The lack of substantial amplitude boosting of the third AP in the high-frequency burst also suggests that in short- and medium-range basal dendrites backpropagating APs were not severely attenuated. Our results show that the AP-failure concept does not apply in all basal dendrites of the rat prefrontal cortex. The majority of synaptic contacts in the basilar dendritic tree actually received significant AP-associated electrical and calcium transients.

Quantitative autoradiography of muscarinic and benzodiazepine receptors in the forebrain of the turtle, Pseudemys scripta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlegel, J.R.; Kriegstein, A.R.

1987-11-22

The distribution of muscarinic and benzodiazepine receptors was investigated in the turtle forebrain by the technique of in vitro receptor autoradiography. Muscarinic binding sites were labeled with 1 nM /sup 3/H-quinuclidinyl benzilate (/sup 3/H-QNB), and benzodiazepine sites were demonstrated with the aid of 1 nM /sup 3/H-flunitrazepam (/sup 3/H-FLU). Autoradiograms generated on /sup 3/H-Ultrofilm apposed to tissue slices revealed regionally specific distributions of muscarinic and benzodiazepine binding sites that are comparable with those for mammalian brain. Dense benzodiazepine binding was found in the anterior olfactory nucleus, the lateral and dorsal cortices, and the dorsal ventricular ridge (DVR), a structure withmore » no clear mammalian homologue. Muscarinic binding sites were most dense in the striatum, accumbens, DVR, lateral geniculate, and the anterior olfactory nucleus. Cortical binding sites were studied in greater detail by quantitative analysis of autoradiograms generated by using emulsion-coated coverslips. Laminar gradients of binding were observed that were specific for each radioligand; /sup 3/H-QNB sites were most dense in the inner molecular layer in all cortical regions, whereas /sup 3/H-FLU binding was generally most concentrated in the outer molecular layer and was least dense through all layers in the dorsomedial cortex. Because pyramidal cells are arranged in register in turtle cortex, the laminar patterns of receptor binding may reflect different receptor density gradients along pyramidal cell dendrites.« less

Growth and Electronic Structure Characterization of (SrCoOx)n :(SrTiO3)1 Superlattices

NASA Astrophysics Data System (ADS)

Cook, Say Young; Andersen, Tassie; Rosenberg, Richard; Hong, Hawoong; Marks, Laurence; Fong, Dillon

We report on the synthesis of a (SrCoOx)1 :(SrTiO3)1 superlattice by oxide molecular beam epitaxy and the characterization of its electronic structure by soft x-ray spectroscopy. X-ray photoelectron and absorption spectroscopy reveal that Ti remains octahedrally coordinated with a 4 + oxidation state, while the Co oxidation state is intermediate of 3 + and 4 +. Despite having the same half an oxygen vacancy per Co atom found in brownmillerite SrCoO2.5, which consists of alternating tetrahedral and octahedral layers of Co, the confinement of oxygen vacancies to isolated single atomic layers of SrCoOx stabilizes square pyramidal coordination of Co, as observed by the linear dichroism in the Co 2p-3d x-ray absorption. The corresponding stabilization of Co4+ along with Co3 + within the square pyramidal SrCoO2.5 layers gives rise to a Fermi-edge step observed at strong Co 2p-3d resonance in the resonant photoemission spectroscopy of the valence band, and reveals a band gap of 1.7 eV. Comparisons with a Sr(Co,Ti)Ox alloy and a (SrCoOx)2 :(SrTiO3)1 superlattice also will also be presented. The obtained results demonstrate artificial superlattices as effective means to defect engineer complex oxides by harnessing the confinement of oxygen vacancies to control the oxygen coordination environment of the transition metal.

Durability Enhancement of a Microelectromechanical System-Based Liquid Droplet Lens

NASA Astrophysics Data System (ADS)

Kyoo Lee, June; Park, Kyung-Woo; Kim, Hak-Rin; Kong, Seong Ho

2010-06-01

In this paper, we propose methods to enhance the durability of a microelectromechanical system (MEMS)-based liquid droplet lens driven by electrowetting. The enhanced durability of the lens is achieved through not only improvement in quality of dielectric layer for electrowetting by minimizing concentration of coarse pinholes, but also mitigation of physical and electrostatic stresses by reforming lens cavity. Silicon dioxide layer is deposited using plasma enhanced chemical vapor deposition, splitting the process into several steps to minimize the pinhole concentration in the oxide layer. And the stresses-reduced cavity in a form of overturned tetra-angular truncated pyramid with rounded corners, which is based on simulated results, is proposed and realized using silicon wet etching processes combined into anisotropic and isotropic etching.

Nondestructive characterization of textured a-Si:H/c-Si heterojunction solar cell structures with nanometer-scale a-Si:H and In2O3:Sn layers by spectroscopic ellipsometry

NASA Astrophysics Data System (ADS)

Matsuki, Nobuyuki; Fujiwara, Hiroyuki

2013-07-01

Nanometer-scale hydrogenated amorphous silicon (a-Si:H) layers formed on crystalline silicon (c-Si) with pyramid-shaped textures have been characterized by spectroscopic ellipsometry (SE) using a tilt angle measurement configuration, in an attempt to establish a nondestructive method for the structural characterization of the a-Si:H/c-Si heterojunction solar cells. By applying an a-Si:H dielectric function model developed recently, the thickness and SiH2 content of the a-Si:H layer have been determined even on the textured substrates. Furthermore, from the SE analysis incorporating the Drude model, the carrier properties of the In2O3:Sn layers in the textured solar-cell structure have been characterized.

Regional expression and ultrastructural localization of EphA7 in the hippocampus and cerebellum of adult rat.

PubMed

Amegandjin, Clara A; Jammow, Wafaa; Laforest, Sylvie; Riad, Mustapha; Baharnoori, Moogeh; Badeaux, Frédérique; DesGroseillers, Luc; Murai, Keith K; Pasquale, Elena B; Drolet, Guy; Doucet, Guy

2016-08-15

EphA7 is expressed in the adult central nervous system (CNS), where its roles are yet poorly defined. We mapped its distribution using in situ hybridization (ISH) and immunohistochemistry (IHC) combined with light (LM) and electron microscopy (EM) in adult rat and mouse brain. The strongest ISH signal was in the hippocampal pyramidal and granule cell layers. Moderate levels were detected in habenula, striatum, amygdala, the cingulate, piriform and entorhinal cortex, and in cerebellum, notably the Purkinje cell layer. The IHC signal distribution was consistent with ISH results, with transport of the protein to processes, as exemplified in the hippocampal neuropil layers and weakly stained pyramidal cell layers. In contrast, in the cerebellum, the Purkinje cell bodies were the most strongly immunolabeled elements. EM localized the cell surface-expression of EphA7 essentially in postsynaptic densities (PSDs) of dendritic spines and shafts, and on some astrocytic leaflets, in both hippocampus and cerebellum. Perikaryal and dendritic labeling was mostly intracellular, associated with the synthetic and trafficking machineries. Immunopositive vesicles were also observed in axons and axon terminals. Quantitative analysis in EM showed significant differences in the frequency of labeled elements between regions. Notably, labeled dendrites were ∼3-5 times less frequent in cerebellum than in hippocampus, but they were individually endowed with ∼10-40 times higher frequencies of PSDs, on their shafts and spines. The cell surface localization of EphA7, being preferentially in PSDs, and in perisynaptic astrocytic leaflets, provides morphologic evidence that EphA7 plays key roles in adult CNS synaptic maintenance, plasticity, or function. J. Comp. Neurol. 524:2462-2478, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Photodetectors using III-V nitrides

DOEpatents

Moustakas, T.D.; Misra, M.

1997-10-14

A photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The photodetector includes a substrate with interdigitated electrodes formed on its surface. The substrate has a sapphire base layer, a buffer layer formed from a III-V nitride and a single crystal III-V nitride film. The three layers are formed by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-assisted MBE). Use of the ECR-assisted MBE process allows control and predetermination of the electrical properties of the photodetector. 24 figs.

Photodetectors using III-V nitrides

DOEpatents

Moustakas, Theodore D.; Misra, Mira

1997-01-01

A photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The photodetector includes a substrate with interdigitated electrodes formed on its surface. The substrate has a sapphire base layer, a buffer layer formed from a III-V nitride and a single crystal III-V nitride film. The three layers are formed by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-assisted MBE). Use of the ECR-assisted MBE process allows control and predetermination of the electrical properties of the photodetector.

High-pressure endurable flexible tactile actuator based on microstructured dielectric elastomer

NASA Astrophysics Data System (ADS)

Pyo, Dongbum; Ryu, Semin; Kyung, Ki-Uk; Yun, Sungryul; Kwon, Dong-Soo

2018-02-01

We demonstrate a robust flexible tactile actuator that is capable of working under high external pressures. The tactile actuator is based on a pyramidal microstructured dielectric elastomer layer inducing variation in both mechanical and dielectric properties. The vibrational performance of the actuator can be modulated by changing the geometric parameter of the microstructures. We evaluated the performance of the actuator under high-pressure loads up to 25 kPa, which is over the typical range of pressure applied when humans touch or manipulate objects. Due to the benefit of nonlinearity of the pyramidal structure, the actuator could maintain high mechanical output under various external pressures in the frequency range of 100-200 Hz, which is the most sensitive to vibration acceleration for human finger pads. The responses are not only fast, reversible, and highly durable under consecutive cyclic operations, but also large enough to impart perceivable vibrations for haptic feedback on practical wearable device applications.

Parallel regulation of feedforward inhibition and excitation during whisker map plasticity

PubMed Central

House, David RC; Elstrott, Justin; Koh, Eileen; Chung, Jason; Feldman, Daniel E.

2011-01-01

Sensory experience drives robust plasticity of sensory maps in cerebral cortex, but the role of inhibitory circuits in this process is not fully understood. We show that classical deprivation-induced whisker map plasticity in layer 2/3 (L2/3) of rat somatosensory (S1) cortex involves robust weakening of L4-L2/3 feedforward inhibition. This weakening was caused by reduced L4 excitation onto L2/3 fast-spiking (FS) interneurons, which mediate sensitive feedforward inhibition, and was partially offset by strengthening of unitary FS to L2/3 pyramidal cell synapses. Weakening of feedforward inhibition paralleled the known weakening of feedforward excitation, so that mean excitatory-inhibitory balance and timing onto L2/3 pyramidal cells were preserved. Thus, reduced feedforward inhibition is a covert compensatory process that can maintain excitatory-inhibitory balance during classical deprivation-induced Hebbian map plasticity. PMID:22153377

Network Supervision of Adult Experience and Learning Dependent Sensory Cortical Plasticity.

PubMed

Blake, David T

2017-06-18

The brain is capable of remodeling throughout life. The sensory cortices provide a useful preparation for studying neuroplasticity both during development and thereafter. In adulthood, sensory cortices change in the cortical area activated by behaviorally relevant stimuli, by the strength of response within that activated area, and by the temporal profiles of those responses. Evidence supports forms of unsupervised, reinforcement, and fully supervised network learning rules. Studies on experience-dependent plasticity have mostly not controlled for learning, and they find support for unsupervised learning mechanisms. Changes occur with greatest ease in neurons containing α-CamKII, which are pyramidal neurons in layers II/III and layers V/VI. These changes use synaptic mechanisms including long term depression. Synaptic strengthening at NMDA-containing synapses does occur, but its weak association with activity suggests other factors also initiate changes. Studies that control learning find support of reinforcement learning rules and limited evidence of other forms of supervised learning. Behaviorally associating a stimulus with reinforcement leads to a strengthening of cortical response strength and enlarging of response area with poor selectivity. Associating a stimulus with omission of reinforcement leads to a selective weakening of responses. In some preparations in which these associations are not as clearly made, neurons with the most informative discharges are relatively stronger after training. Studies analyzing the temporal profile of responses associated with omission of reward, or of plasticity in studies with different discriminanda but statistically matched stimuli, support the existence of limited supervised network learning. © 2017 American Physiological Society. Compr Physiol 7:977-1008, 2017. Copyright © 2017 John Wiley & Sons, Inc.

Neocortical neuron types in Xenarthra and Afrotheria: implications for brain evolution in mammals.

PubMed

Sherwood, Chet C; Stimpson, Cheryl D; Butti, Camilla; Bonar, Christopher J; Newton, Alisa L; Allman, John M; Hof, Patrick R

2009-02-01

Interpreting the evolution of neuronal types in the cerebral cortex of mammals requires information from a diversity of species. However, there is currently a paucity of data from the Xenarthra and Afrotheria, two major phylogenetic groups that diverged close to the base of the eutherian mammal adaptive radiation. In this study, we used immunohistochemistry to examine the distribution and morphology of neocortical neurons stained for nonphosphorylated neurofilament protein, calbindin, calretinin, parvalbumin, and neuropeptide Y in three xenarthran species-the giant anteater (Myrmecophaga tridactyla), the lesser anteater (Tamandua tetradactyla), and the two-toed sloth (Choloepus didactylus)-and two afrotherian species-the rock hyrax (Procavia capensis) and the black and rufous giant elephant shrew (Rhynchocyon petersi). We also studied the distribution and morphology of astrocytes using glial fibrillary acidic protein as a marker. In all of these species, nonphosphorylated neurofilament protein-immunoreactive neurons predominated in layer V. These neurons exhibited diverse morphologies with regional variation. Specifically, high proportions of atypical neurofilament-enriched neuron classes were observed, including extraverted neurons, inverted pyramidal neurons, fusiform neurons, and other multipolar types. In addition, many projection neurons in layers II-III were found to contain calbindin. Among interneurons, parvalbumin- and calbindin-expressing cells were generally denser compared to calretinin-immunoreactive cells. We traced the evolution of certain cortical architectural traits using phylogenetic analysis. Based on our reconstruction of character evolution, we found that the living xenarthrans and afrotherians show many similarities to the stem eutherian mammal, whereas other eutherian lineages display a greater number of derived traits.

Relationships between structure, in vivo function and long-range axonal target of cortical pyramidal tract neurons.

PubMed

Rojas-Piloni, Gerardo; Guest, Jason M; Egger, Robert; Johnson, Andrew S; Sakmann, Bert; Oberlaender, Marcel

2017-10-11

Pyramidal tract neurons (PTs) represent the major output cell type of the neocortex. To investigate principles of how the results of cortical processing are broadcasted to different downstream targets thus requires experimental approaches, which provide access to the in vivo electrophysiology of PTs, whose subcortical target regions are identified. On the example of rat barrel cortex (vS1), we illustrate that retrograde tracer injections into multiple subcortical structures allow identifying the long-range axonal targets of individual in vivo recorded PTs. Here we report that soma depth and dendritic path lengths within each cortical layer of vS1, as well as spiking patterns during both periods of ongoing activity and during sensory stimulation, reflect the respective subcortical target regions of PTs. We show that these cellular properties result in a structure-function parameter space that allows predicting a PT's subcortical target region, without the need to inject multiple retrograde tracers.The major output cell type of the neocortex - pyramidal tract neurons (PTs) - send axonal projections to various subcortical areas. Here the authors combined in vivo recordings, retrograde tracings, and reconstructions of PTs in rat somatosensory cortex to show that PT structure and activity can predict specific subcortical targets.

[Peripheral facial nerve lesion induced long-term dendritic retraction in pyramidal cortico-facial neurons].

PubMed

Urrego, Diana; Múnera, Alejandro; Troncoso, Julieta

2011-01-01

Little evidence is available concerning the morphological modifications of motor cortex neurons associated with peripheral nerve injuries, and the consequences of those injuries on post lesion functional recovery. Dendritic branching of cortico-facial neurons was characterized with respect to the effects of irreversible facial nerve injury. Twenty-four adult male rats were distributed into four groups: sham (no lesion surgery), and dendritic assessment at 1, 3 and 5 weeks post surgery. Eighteen lesion animals underwent surgical transection of the mandibular and buccal branches of the facial nerve. Dendritic branching was examined by contralateral primary motor cortex slices stained with the Golgi-Cox technique. Layer V pyramidal (cortico-facial) neurons from sham and injured animals were reconstructed and their dendritic branching was compared using Sholl analysis. Animals with facial nerve lesions displayed persistent vibrissal paralysis throughout the five week observation period. Compared with control animal neurons, cortico-facial pyramidal neurons of surgically injured animals displayed shrinkage of their dendritic branches at statistically significant levels. This shrinkage persisted for at least five weeks after facial nerve injury. Irreversible facial motoneuron axonal damage induced persistent dendritic arborization shrinkage in contralateral cortico-facial neurons. This morphological reorganization may be the physiological basis of functional sequelae observed in peripheral facial palsy patients.

Type III Neuregulin 1 Is Required for Multiple Forms of Excitatory Synaptic Plasticity of Mouse Cortico-Amygdala Circuits

PubMed Central

Emmetsberger, Jaime; Talmage, David A.; Role, Lorna W.

2013-01-01

The amygdala plays an important role in the formation and storage of memories associated with emotional events. The cortical glutamatergic inputs onto pyramidal neurons in the basolateral nucleus of the amygdala (BLA) contribute to this process. As the interaction between neuregulin 1 (Nrg1) and its ErbB receptors has been implicated in the pathological mechanisms of schizophrenia, loss of Nrg1 may disrupt cortical–amygdala neural circuits, resulting in altered processing of salient memories. Here we show that Nrg1 is critical in multiple forms of plasticity of cortical projections to pyramidal neurons of the BLA. The miniature EPSCs in Nrg1 heterozygous animals have a faster time constant of decay and evoked synaptic currents have a smaller NMDA/AMPA ratio than those recorded in wild-type (WT) littermates. Both high-frequency electrical stimulation of cortical inputs and θ burst stimulation combined with nicotine exposure results in long-lasting potentiation in WT animals. However, the same manipulations have little to no effect on glutamatergic synaptic plasticity in the BLA from Nrg1 heterozygous mice. Comparison of WT, Nrg1 heterozygous animals and α7 nicotinic receptor heterozygous mice reveals that the sustained phase of potentiation of glutamatergic transmission after θ burst stimulation with or without nicotine only occurs in the WT mice. Together, these findings support the idea that type III Nrg1 is essential to multiple aspects of the modulation of excitatory plasticity at cortical–BLA synapses. PMID:23739962

Methods for fabricating thin film III-V compound solar cell

DOEpatents

Pan, Noren; Hillier, Glen; Vu, Duy Phach; Tatavarti, Rao; Youtsey, Christopher; McCallum, David; Martin, Genevieve

2011-08-09

The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

Bidirectional Hebbian Plasticity Induced by Low-Frequency Stimulation in Basal Dendrites of Rat Barrel Cortex Layer 5 Pyramidal Neurons.

PubMed

Díez-García, Andrea; Barros-Zulaica, Natali; Núñez, Ángel; Buño, Washington; Fernández de Sevilla, David

2017-01-01

According to Hebb's original hypothesis (Hebb, 1949), synapses are reinforced when presynaptic activity triggers postsynaptic firing, resulting in long-term potentiation (LTP) of synaptic efficacy. Long-term depression (LTD) is a use-dependent decrease in synaptic strength that is thought to be due to synaptic input causing a weak postsynaptic effect. Although the mechanisms that mediate long-term synaptic plasticity have been investigated for at least three decades not all question have as yet been answered. Therefore, we aimed at determining the mechanisms that generate LTP or LTD with the simplest possible protocol. Low-frequency stimulation of basal dendrite inputs in Layer 5 pyramidal neurons of the rat barrel cortex induces LTP. This stimulation triggered an EPSP, an action potential (AP) burst, and a Ca 2+ spike. The same stimulation induced LTD following manipulations that reduced the Ca 2+ spike and Ca 2+ signal or the AP burst. Low-frequency whisker deflections induced similar bidirectional plasticity of action potential evoked responses in anesthetized rats. These results suggest that both in vitro and in vivo similar mechanisms regulate the balance between LTP and LTD. This simple induction form of bidirectional hebbian plasticity could be present in the natural conditions to regulate the detection, flow, and storage of sensorimotor information.

An Augmented Two-Layer Model Captures Nonlinear Analog Spatial Integration Effects in Pyramidal Neuron Dendrites

PubMed Central

JADI, MONIKA P.; BEHABADI, BARDIA F.; POLEG-POLSKY, ALON; SCHILLER, JACKIE; MEL, BARTLETT W.

2014-01-01

In pursuit of the goal to understand and eventually reproduce the diverse functions of the brain, a key challenge lies in reverse engineering the peculiar biology-based “technology” that underlies the brain’s remarkable ability to process and store information. The basic building block of the nervous system is the nerve cell, or “neuron,” yet after more than 100 years of neurophysiological study and 60 years of modeling, the information processing functions of individual neurons, and the parameters that allow them to engage in so many different types of computation (sensory, motor, mnemonic, executive, etc.) remain poorly understood. In this paper, we review both historical and recent findings that have led to our current understanding of the analog spatial processing capabilities of dendrites, the major input structures of neurons, with a focus on the principal cell type of the neocortex and hippocampus, the pyramidal neuron (PN). We encapsulate our current understanding of PN dendritic integration in an abstract layered model whose spatially sensitive branch-subunits compute multidimensional sigmoidal functions. Unlike the 1-D sigmoids found in conventional neural network models, multidimensional sigmoids allow the cell to implement a rich spectrum of nonlinear modulation effects directly within their dendritic trees. PMID:25554708

Ultrastructural Alterations of Von Economo Neurons in the Anterior Cingulate Cortex in Schizophrenia.

PubMed

Krause, Martin; Theiss, Carsten; Brüne, Martin

2017-11-01

Von Economo neurons (VENs) are large bipolar projection neurons mainly located in layer Vb of anterior cingulate cortex (ACC) and anterior insula. Both regions are involved in cognitive and emotional procedures and are functionally and anatomically altered in schizophrenia. Although the detailed function of VEN remains unclear, it has been suggested that these neurons are involved in the pathomechanism of schizophrenia. Here, we were interested in the question whether or not the VEN of schizophrenia patients would show abnormalities at the ultrastructural level. Accordingly, we examined the amount of lysosomal aggregations of the VEN in post-mortem tissue of patients with schizophrenia, bipolar disorder and psychologically unaffected individuals, and compared the findings with aggregations in adjacent pyramidal cells in layer Vb of the ACC. VEN of patients with schizophrenia, and to a lesser degree individuals with bipolar disorder contained significantly more lysosomal aggregations compared with tissue from unaffected controls. Specifically, the larger amount of lysosomal aggregations in schizophrenia seemed to be selective for VEN, with no differences occurring in pyramidal cells. These findings may indicate that the VEN of schizophrenia patients are selectively vulnerable to neuronal damage. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:2017-2024, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Bidirectional Hebbian Plasticity Induced by Low-Frequency Stimulation in Basal Dendrites of Rat Barrel Cortex Layer 5 Pyramidal Neurons

PubMed Central

Díez-García, Andrea; Barros-Zulaica, Natali; Núñez, Ángel; Buño, Washington; Fernández de Sevilla, David

2017-01-01

According to Hebb's original hypothesis (Hebb, 1949), synapses are reinforced when presynaptic activity triggers postsynaptic firing, resulting in long-term potentiation (LTP) of synaptic efficacy. Long-term depression (LTD) is a use-dependent decrease in synaptic strength that is thought to be due to synaptic input causing a weak postsynaptic effect. Although the mechanisms that mediate long-term synaptic plasticity have been investigated for at least three decades not all question have as yet been answered. Therefore, we aimed at determining the mechanisms that generate LTP or LTD with the simplest possible protocol. Low-frequency stimulation of basal dendrite inputs in Layer 5 pyramidal neurons of the rat barrel cortex induces LTP. This stimulation triggered an EPSP, an action potential (AP) burst, and a Ca2+ spike. The same stimulation induced LTD following manipulations that reduced the Ca2+ spike and Ca2+ signal or the AP burst. Low-frequency whisker deflections induced similar bidirectional plasticity of action potential evoked responses in anesthetized rats. These results suggest that both in vitro and in vivo similar mechanisms regulate the balance between LTP and LTD. This simple induction form of bidirectional hebbian plasticity could be present in the natural conditions to regulate the detection, flow, and storage of sensorimotor information. PMID:28203145

A novel DPP6 isoform (DPP6-E) can account for differences between neuronal and reconstituted A-type K(+) channels.

PubMed

Maffie, Jonathon; Blenkinsop, Timothy; Rudy, Bernardo

2009-01-16

The channels mediating most of the somatodendritic A-type K(+) current in neurons are thought to be ternary complexes of Kv4 pore-forming subunits and two types of auxiliary subunits, the K(+) channel interacting proteins (KChIPs) and dipeptidyl-peptidase-like (DPPL) proteins. The channels expressed in heterologous expression systems by mixtures of Kv4.2, KChIP1 and DPP6-S resemble in many properties the A-type current in hippocampal CA1 pyramidal neurons and cerebellar granule cells, neurons with prominent A-type K(+) currents. However, the native currents have faster kinetics. Moreover, the A-type currents in neurons in intermediary layers of the superior colliculus have even faster inactivating rates. We have characterized a new DPP6 spliced isoform, DPP6-E, that produces in heterologous cells ternary Kv4 channels with very fast kinetics. DPP6-E is selectively expressed in a few neuronal populations in brain including cerebellar granule neurons, hippocampal pyramidal cells and neurons in intermediary layers of the superior colliculus. The effects of DPP6-E explain past discrepancies between reconstituted and native Kv4 channels in some neurons, and contributes to the diversity of A-type K(+) currents in neurons.

Type III Neuregulin-1 is required for normal sensorimotor gating, memory related behaviors and cortico-striatal circuit components

PubMed Central

Chen, Ying-Jiun J.; Johnson, Madeleine A.; Lieberman, Michael D.; Goodchild, Rose E.; Schobel, Scott; Lewandowski, Nicole; Rosoklija, Gorazd; Liu, Ruei-Che; Gingrich, Jay A.; Small, Scott; Moore, Holly; Dwork, Andrew J.; Talmage, David A.; Role, Lorna W.

2008-01-01

Neuregulin-1 (Nrg1)/erbB signaling regulates neuronal development, migration, myelination, and synaptic maintenance. The Nrg1 gene is a schizophrenia susceptibility gene. To understand the contribution of Nrg1 signaling to adult brain structure and behaviors, we have studied the regulation of Type III Nrg1 expression and evaluated the effect of decreased expression of the Type III Nrg1 isoforms. Type III Nrg1 is transcribed by a promoter distinct from those for other Nrg1 isoforms and, in the adult brain, is expressed in the medial prefrontal cortex, ventral hippocampus and ventral subiculum, regions involved in the regulation of sensorimotor gating and short term memory. Adult heterozygous mutant mice with a targeted disruption for Type III Nrg1 (Nrg1tm1.1Lwr+/-) have enlarged lateral ventricles and decreased dendritic spine density on subicular pyramidal neurons. MRI imaging of Type III Nrg1 heterozygous mice revealed hypo-function in the medial prefrontal cortex and the hippocampal CA1 and subiculum regions. Type III Nrg1 heterozygous mice also have impaired performance on delayed alternation memory tasks, and deficits in prepulse inhibition (PPI). Chronic nicotine treatment eliminated differences in PPI between Type III Nrg1 heterozygous mice and their wild type littermates. Our findings demonstrate a role of Type III Nrg1-signaling in the maintenance of cortico-striatal components, and in the neural circuits involved in sensorimotor gating and short term memory. PMID:18596162

Spiking in auditory cortex following thalamic stimulation is dominated by cortical network activity

PubMed Central

Krause, Bryan M.; Raz, Aeyal; Uhlrich, Daniel J.; Smith, Philip H.; Banks, Matthew I.

2014-01-01

The state of the sensory cortical network can have a profound impact on neural responses and perception. In rodent auditory cortex, sensory responses are reported to occur in the context of network events, similar to brief UP states, that produce “packets” of spikes and are associated with synchronized synaptic input (Bathellier et al., 2012; Hromadka et al., 2013; Luczak et al., 2013). However, traditional models based on data from visual and somatosensory cortex predict that ascending sensory thalamocortical (TC) pathways sequentially activate cells in layers 4 (L4), L2/3, and L5. The relationship between these two spatio-temporal activity patterns is unclear. Here, we used calcium imaging and electrophysiological recordings in murine auditory TC brain slices to investigate the laminar response pattern to stimulation of TC afferents. We show that although monosynaptically driven spiking in response to TC afferents occurs, the vast majority of spikes fired following TC stimulation occurs during brief UP states and outside the context of the L4>L2/3>L5 activation sequence. Specifically, monosynaptic subthreshold TC responses with similar latencies were observed throughout layers 2–6, presumably via synapses onto dendritic processes located in L3 and L4. However, monosynaptic spiking was rare, and occurred primarily in L4 and L5 non-pyramidal cells. By contrast, during brief, TC-induced UP states, spiking was dense and occurred primarily in pyramidal cells. These network events always involved infragranular layers, whereas involvement of supragranular layers was variable. During UP states, spike latencies were comparable between infragranular and supragranular cells. These data are consistent with a model in which activation of auditory cortex, especially supragranular layers, depends on internally generated network events that represent a non-linear amplification process, are initiated by infragranular cells and tightly regulated by feed-forward inhibitory cells. PMID:25285071

Medical high-resolution image sharing and electronic whiteboard system: A pure-web-based system for accessing and discussing lossless original images in telemedicine.

PubMed

Qiao, Liang; Li, Ying; Chen, Xin; Yang, Sheng; Gao, Peng; Liu, Hongjun; Feng, Zhengquan; Nian, Yongjian; Qiu, Mingguo

2015-09-01

There are various medical image sharing and electronic whiteboard systems available for diagnosis and discussion purposes. However, most of these systems ask clients to install special software tools or web plug-ins to support whiteboard discussion, special medical image format, and customized decoding algorithm of data transmission of HRIs (high-resolution images). This limits the accessibility of the software running on different devices and operating systems. In this paper, we propose a solution based on pure web pages for medical HRIs lossless sharing and e-whiteboard discussion, and have set up a medical HRI sharing and e-whiteboard system, which has four-layered design: (1) HRIs access layer: we improved an tile-pyramid model named unbalanced ratio pyramid structure (URPS), to rapidly share lossless HRIs and to adapt to the reading habits of users; (2) format conversion layer: we designed a format conversion engine (FCE) on server side to real time convert and cache DICOM tiles which clients requesting with window-level parameters, to make browsers compatible and keep response efficiency to server-client; (3) business logic layer: we built a XML behavior relationship storage structure to store and share users' behavior, to keep real time co-browsing and discussion between clients; (4) web-user-interface layer: AJAX technology and Raphael toolkit were used to combine HTML and JavaScript to build client RIA (rich Internet application), to meet clients' desktop-like interaction on any pure webpage. This system can be used to quickly browse lossless HRIs, and support discussing and co-browsing smoothly on any web browser in a diversified network environment. The proposal methods can provide a way to share HRIs safely, and may be used in the field of regional health, telemedicine and remote education at a low cost. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Synthesis of Schiff base 24-membered trivalent transition metal derivatives with their anti-inflammation and antimicrobial evaluation

NASA Astrophysics Data System (ADS)

Kumar, Gajendra; Devi, Shoma; Kumar, Dharmendra

2016-03-01

The paper presents the synthesis of macrocyclic complexes [{M(C52H36N12O4)X}X2] of Cr(III), Mn(III) and Fe(III) with Schiff base ligand (C52H36N12O4) obtained through the condensation of 1,4-dicarbonyl phenyl dihydrazide with 1,2-di(1H-indol-1-yl)ethane-1,2-dione. The newly formed Schiff base and its complexes have been characterized with the help of elemental analysis, condensation measurements, magnetic measurements and their structure configuration have been determined by various spectroscopic (electronic, IR, 1H NMR, 13C NMR, GCMS) techniques. The electronic spectra of the complexes indicate a five coordinate square pyramidal geometry of the center metal ion. These metal complexes and ligand were tested for their anti-inflammation and antimicrobial inhibiting potential and compared with standard drugs Phenyl butazone (anti-inflammation), Imipenem (antibacterial) and Miconazole (antifungal).

[Synapse maturation and autism: learning from neuroligin model mice].

PubMed

Tabuchi, Katsuhiko; Chang, WenHsin; Hang, WenHsin; Asgar, Nur Farehan; Asgar, Nur Farehan Mohamed; Pramanik, Gopal

2014-02-01

Autism is a neurodevelopmental disorder characterized by impairments in social interaction, communication, and restricted and repetitive behavior. Synaptic defects have been implicated in autism; nevertheless, the cause is still largely unknown. A mutation that substitutes cysteine for arginine at residue 451 of Neuroligin-3 (R451C) is the first monogenic mutation identified in idiopathic autism patients. To study the relationship between this mutation and autism, we generated knock-in mice that recapitulated this mutation. The knock-in mice were born and grew up normally without showing any major physical phenotypes, but showed a deficit in social interaction. We studied synaptic function in the layer II/III pyramidal neurons in the somatosensory cortex and found inhibitory synaptic transmission was enhanced in the knock-in mice. The administration of GABA blocker rescued social interaction, suggesting that this caused autistic behavior in these mice. We also found, by Morris water maze test, that spatial learning and memory were significantly enhanced in the knock-in mice. Electrophysiology in the CA1 region of the hippocampus revealed that LTP, the NMDA/AMPA ratio, and NR2B function were enhanced, indicating that synaptic maturation was impaired in the knock-in mice. This may cause the deficit in social behavior and extraordinary memory ability occasionally seen in autistic patients.

GaAs/Ge crystals grown on Si substrates patterned down to the micron scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taboada, A. G., E-mail: gonzalez@phys.ethz.ch; Kreiliger, T.; Falub, C. V.

Monolithic integration of III-V compounds into high density Si integrated circuits is a key technological challenge for the next generation of optoelectronic devices. In this work, we report on the metal organic vapor phase epitaxy growth of strain-free GaAs crystals on Si substrates patterned down to the micron scale. The differences in thermal expansion coefficient and lattice parameter are adapted by a 2-μm-thick intermediate Ge layer grown by low-energy plasma enhanced chemical vapor deposition. The GaAs crystals evolve during growth towards a pyramidal shape, with lateral facets composed of (111) planes and an apex formed by (137) and (001) surfaces.more » The influence of the anisotropic GaAs growth kinetics on the final morphology is highlighted by means of scanning and transmission electron microscopy measurements. The effect of the Si pattern geometry, substrate orientation, and crystal aspect ratio on the GaAs structural properties was investigated by means of high resolution X-ray diffraction. The thermal strain relaxation process of GaAs crystals with different aspect ratio is discussed within the framework of linear elasticity theory by Finite Element Method simulations based on realistic geometries extracted from cross-sectional scanning electron microscopy images.« less

Carbonate deposition, Pyramid Lake subbasin, Nevada: 1. Sequence of formation and elevational distribution of carbonate deposits (Tufas)

USGS Publications Warehouse

Benson, L.

1994-01-01

During the late Quarternary, the elevation of terrace cutting and carbonate deposition in the Pyramid Lake subbasin were controlled by constancy of lake level imposed by spill to adjoining subbasins. Sill elevations are 1177-1183 m (Mud Lake Slough Sill), 1207 m (Emerson Pass Sill), and 1265 m (Darwin Pass Sill). Carbonate deposition was favored by: (1) hydrologic closure, (2) proximity to a source of calcium, (3) elevated water temperature, and (4) a solid substrate. The thickness and aspect of tufa are a function oflake-level dynamics. Relatively thin sheets and pendant sheets were deposited during a rising or falling lake. The upper parts of thick reef-form tufas have a horizontal aspect and were deposited in a lake which was stabilized by spill to the Carson Desert subbasin. The lower parts of the reef-form tufas are thinner and their outer surface has a vertical aspect, indicating that the lower part formed in a receding lake. The thickest and most complete sequences of tufa are mounds that border the Pyramid Lake shore. The tops of the tallest mounds reach the elevation of the Darwin Pass Sill and many mounds have been eroded to the elevations of the Mud Lake Slough Sill of the Emerson Pass Sill. The sequence of tufa formation (from oldest to youngest) displayed in these mounds is: (1) a beachrock containing carbonate-cemented volcanic cobbles, (2) broken and eroded old spheroids that contain thinolitic tufa and an outer rind of dense laminated tufa, (3) large cylindrical (tubular) tufas capped by (4) coatings of old dense tufas, and (5) several generations of old branching tufa commonly associated with thin, platy tufas and coatings of thinolitic tufa, (6) young spheroids that contain poorly oriented young thinolitic tufa in the center and several generations of radially oriented young thinolitic tufas near the outer edge, (7) a transitional thinolite-to-branching tufa, (8) two or more layers of young branching tufa, (9) a 0.5-cm-thick layer of fine-grained dolomite, (10) a 2-cm-thick layer of young dense laminated tufa, (11) a 0.1-cm-thick layer of encrusting tufa that was covered by a beach deposit and (12) a 1.0-cm-thick layer of porous encrusting tufa that coated the beach deposit and the sides of tufa mounds. The elevational ranges of the principal varieties of tufa are not related to terrace or spill elevations. It seems likely that the distribution of tufa varieties is related to variation in the thermal structure or chemistry of Lake Lahontan. It is hypothesized that the thinolitic tufa (ikaite) formed in the near freezing hypolimnion and the braching tufa (calcite) formed in the seasonally warmer epiliminion of the lake. ?? 1994.

Surface-enhanced Raman scattering of amorphous TiO2 thin films by gold nanostructures: Revealing first layer effect with thickness variation

NASA Astrophysics Data System (ADS)

Degioanni, S.; Jurdyc, A.-M.; Bessueille, F.; Coulm, J.; Champagnon, B.; Vouagner, D.

2013-12-01

In this paper, amorphous titanium dioxide (TiO2) thin films have been deposited on a commercially available Klarite substrate using the sol-gel process to produce surface-enhanced Raman scattering (SERS). The substrate consists of square arrays of micrometer-sized pyramidal pits in silicon with a gold coating. Several thin TiO2 layers have been deposited on the surface to study the influence of film thickness. Ultimately, we obtained information on SERS of an amorphous TiO2 layer by gold nanostructures, whose range is less than a few nanometers. Mechanisms responsible for the enhancement are the product of concomitant chemical and electromagnetic effects with an important contribution from plasmon-induced charge transfer.

Chronic administration of resveratrol prevents morphological changes in prefrontal cortex and hippocampus of aged rats.

PubMed

Monserrat Hernández-Hernández, Elizabeth; Serrano-García, Carolina; Antonio Vázquez-Roque, Rubén; Díaz, Alfonso; Monroy, Elibeth; Rodríguez-Moreno, Antonio; Florán, Benjamin; Flores, Gonzalo

2016-05-01

Resveratrol may induce its neuroprotective effects by reducing oxidative damage and chronic inflammation apart from improving vascular function and activating longevity genes, it also has the ability to promote the activity of neurotrophic factors. Morphological changes in dendrites of the pyramidal neurons of the prefrontal cortex (PFC) and hippocampus have been reported in the brain of aging humans, or in humans with neurodegenerative diseases such as Alzheimer's disease. These changes are reflected particularly in the decrement of both the dendritic tree and spine density. Here we evaluated the effect of resveratrol on the dendrites of pyramidal neurons of the PFC (Layers 3 and 5), CA1- and CA3-dorsal hippocampus (DH) as well as CA1-ventral hippocampus, dentate gyrus (DG), and medium spiny neurons of the nucleus accumbens of aged rats. 18-month-old rats were administered resveratrol (20 mg/kg, orally) daily for 60 days. Dendritic morphology was studied by the Golgi-Cox stain procedure, followed by Sholl analysis on 20-month-old rats. In all resveratrol-treated rats, a significant increase in dendritic length and spine density in pyramidal neurons of the PFC, CA1, and CA3 of DH was observed. Interestingly, the enhancement in dendritic length was close to the soma in pyramidal neurons of the PFC, whereas in neurons of the DH and DG, the increase in dendritic length was further from the soma. Our results suggest that resveratrol induces modifications of dendritic morphology in the PFC, DH, and DG. These changes may explain the therapeutic effect of resveratrol in aging and in Alzheimer's disease. © 2016 Wiley Periodicals, Inc.

The Microcircuit Concept Applied to Cortical Evolution: from Three-Layer to Six-Layer Cortex

PubMed Central

Shepherd, Gordon M.

2011-01-01

Understanding the principles of organization of the cerebral cortex requires insight into its evolutionary history. This has traditionally been the province of anatomists, but evidence regarding the microcircuit organization of different cortical areas is providing new approaches to this problem. Here we use the microcircuit concept to focus first on the principles of microcircuit organization of three-layer cortex in the olfactory cortex, hippocampus, and turtle general cortex, and compare it with six-layer neocortex. From this perspective it is possible to identify basic circuit elements for recurrent excitation and lateral inhibition that are common across all the cortical regions. Special properties of the apical dendrites of pyramidal cells are reviewed that reflect the specific adaptations that characterize the functional operations in the different regions. These principles of microcircuit function provide a new approach to understanding the expanded functional capabilities elaborated by the evolution of the neocortex. PMID:21647397

Isotopic Evidence for Early Trade in Animals between Old Kingdom Egypt and Canaan.

PubMed

Arnold, Elizabeth R; Hartman, Gideon; Greenfield, Haskel J; Shai, Itzhaq; Babcock, Lindsay E; Maeir, Aren M

2016-01-01

Isotope data from a sacrificial ass and several ovicaprines (sheep/goat) from Early Bronze Age household deposits at Tell es-Safi/Gath, Israel provide direct evidence for the movement of domestic draught/draft and husbandry animals between Old Kingdom Egypt (during the time of the Pyramids) and Early Bronze Age III Canaan (ca. 2900-2500 BCE). Vacillating, bi-directional connections between Egypt and Canaan are known throughout the Early Bronze Age, but here we provide the first concrete evidence of early trade in animals from Egypt to Canaan.

Unsaturated Mn complex decorated hybrid thioarsenates: Syntheses, crystal structures and physical properties

NASA Astrophysics Data System (ADS)

Yue, Cheng-Yang; Lei, Xiao-Wu; Tian, Ya-Wei; Xu, Jing; Bai, Yi-Qun; Wang, Fei; Zhou, Peng-Fei; Liu, Xiao-Fan; Yi, Fei-Yan

2016-03-01

The incorporation of unsaturated [Mn(1,2-dap)]2+, [Mn(1,2-dap)2]2+, [Mn(2,2-bipy)]2+ (1,2-dap=1,2-diaminopropane) complex cations with thioarsenate anions of [AsIIIS3]3- and [AsVS4]3- led to three new hybrid manganese thioarsenates, namely, [Mn(1,2-dap)]2MnAs2S6 (1), [Mn(1,2-dap)2]{[Mn(1,2-dap)]2As2S8} (2) and (NH4)[Mn(2,2-bipy)2]AsS4 (3). In compound 1, the unsaturated [Mn(1,2-dap)]2+ complexes, [MnS4]6- tetrahedra and [AsIIIS3]3- trigonal-pyramids are condensed to form the 1D [Mn(1,2-dap)]2MnAs2S6 chain, whereas compound 2 features 2D layer composed of [Mn(1,2-dap)]2+ and [Mn(1,2-dap)2]2+ complexes as well as [AsVS4]3- tetrahedral units. For compound 3, two [AsVS4]3- anions bridge two [Mn(2,2-bipy)]2+ complex cations into a butterfly like {[Mn(2,2-bipy)]2As2S8}2- anionic unit. Magnetic measurements indicate the ferrimagnetic behavior for compound 1 and antiferromagnetic (AF) behaviors for compounds 2-3. The UV-vis diffuse-reflectance measurements and electronic structural calculations based on density functional theory (DFT) revealed the title compounds belong to semiconductors with band gaps of 2.63, 2.21, and 1.97 eV, respectively. The narrow band-gap of compound 3 led to the efficient and stable photocatalytic degradation activity over organic pollutant than N-doped P25 under visible light irradiation.

Morphologic Integration of Hilar Ectopic Granule Cells into Dentate Gyrus Circuitry in the Pilocarpine Model of Temporal Lobe Epilepsy

PubMed Central

Cameron, Michael C.; Zhan, Ren-Zhi; Nadler, J. Victor

2014-01-01

After pilocarpine-induced status epilepticus, many granule cells born into the postseizure environment migrate aberrantly into the dentate hilus. Hilar ectopic granule cells (HEGCs) are hyperexcitable and may therefore increase circuit excitability. This study determined the distribution of their axons and dendrites. HEGCs and normotopic granule cells were filled with biocytin during whole-cell patch clamp recording in hippocampal slices from pilocarpine-treated rats. The apical dendrite of 86% of the biocytin-labeled HEGCs extended to the outer edge of the dentate molecular layer. The total length and branching of HEGC apical dendrites that penetrated the molecular layer were significantly reduced compared with apical dendrites of normotopic granule cells. HEGCs were much more likely to have a hilar basal dendrite than normotopic granule cells. They were about as likely as normotopic granule cells to project to CA3 pyramidal cells within the slice, but were much more likely to send at least one recurrent mossy fiber into the molecular layer. HEGCs with burst capability had less well-branched apical dendrites than nonbursting HEGCs, their dendrites were more likely to be confined to the hilus, and some exhibited dendritic features similar to those of immature granule cells. HEGCs thus have many paths along which to receive synchronized activity from normotopic granule cells and to transmit their own hyperactivity to both normotopic granule cells and CA3 pyramidal cells. They may therefore contribute to the highly interconnected granule cell hubs that have been proposed as crucial to development of a hyperexcitable, potentially seizure-prone circuit. PMID:21455997

Aberrant excitatory rewiring of layer V pyramidal neurons early after neocortical trauma

PubMed Central

Takahashi, D. Koji; Isabel, Feng Gu; Parada, Shri Vyas; Prince, David A.

2016-01-01

Lesioned neuronal circuits form new functional connections after a traumatic brain injury (TBI). In humans and animal models, aberrant excitatory connections that form after TBI may contribute to the pathogenesis of post-traumatic epilepsy. Partial neocortical isolation (“undercut” or “UC”) leads to altered neuronal circuitry and network hyperexcitability recorded in vivo and in brain slices from chronically lesioned neocortex. Recent data suggest a critical period for maladaptive excitatory circuit formation within the first 3 days post UC injury (Graber and Prince, 1999, 2004; Li et al., 2011, 2012b). The present study focuses on alterations in excitatory connectivity within this critical period. Immunoreactivity (IR) for growth-associated protein (GAP)-43 was increased in the UC cortex 3 days after injury. Some GAP-43-expressing excitatory terminals targeted the somata of layer V pyramidal (Pyr) neurons, a domain usually innervated predominantly by inhibitory terminals. Immunocytochemical analysis of pre- and postsynaptic markers showed that putative excitatory synapses were present on somata of these neurons in UC neocortex. Excitatory postsynaptic currents from UC layer V Pyr cells displayed properties consistent with perisomatic inputs and also reflected an increase in the number of synaptic contacts. Laser scanning photostimulation (LSPS) experiments demonstrated reorganized excitatory connectivity after injury within the UC. Concurrent with these changes, spontaneous epileptiform bursts developed in UC slices. Results suggest that aberrant reorganization of excitatory connectivity contributes to early neocortical hyperexcitability in this model. The findings are relevant for understanding the pathophysiology of neocortical post-traumatic epileptogenesis and are important in terms of the timing of potential prophylactic treatments. PMID:26956396

Aberrant excitatory rewiring of layer V pyramidal neurons early after neocortical trauma.

PubMed

Takahashi, D Koji; Gu, Feng; Parada, Isabel; Vyas, Shri; Prince, David A

2016-07-01

Lesioned neuronal circuits form new functional connections after a traumatic brain injury (TBI). In humans and animal models, aberrant excitatory connections that form after TBI may contribute to the pathogenesis of post-traumatic epilepsy. Partial neocortical isolation ("undercut" or "UC") leads to altered neuronal circuitry and network hyperexcitability recorded in vivo and in brain slices from chronically lesioned neocortex. Recent data suggest a critical period for maladaptive excitatory circuit formation within the first 3days post UC injury (Graber and Prince 1999, 2004; Li et al. 2011, 2012b). The present study focuses on alterations in excitatory connectivity within this critical period. Immunoreactivity (IR) for growth-associated protein (GAP)-43 was increased in the UC cortex 3days after injury. Some GAP-43-expressing excitatory terminals targeted the somata of layer V pyramidal (Pyr) neurons, a domain usually innervated predominantly by inhibitory terminals. Immunocytochemical analysis of pre- and postsynaptic markers showed that putative excitatory synapses were present on somata of these neurons in UC neocortex. Excitatory postsynaptic currents from UC layer V Pyr cells displayed properties consistent with perisomatic inputs and also reflected an increase in the number of synaptic contacts. Laser scanning photostimulation (LSPS) experiments demonstrated reorganized excitatory connectivity after injury within the UC. Concurrent with these changes, spontaneous epileptiform bursts developed in UC slices. Results suggest that aberrant reorganization of excitatory connectivity contributes to early neocortical hyperexcitability in this model. The findings are relevant for understanding the pathophysiology of neocortical post-traumatic epileptogenesis and are important in terms of the timing of potential prophylactic treatments. Copyright © 2016 Elsevier Inc. All rights reserved.

Multi-channel feature dictionaries for RGB-D object recognition

NASA Astrophysics Data System (ADS)

Lan, Xiaodong; Li, Qiming; Chong, Mina; Song, Jian; Li, Jun

2018-04-01

Hierarchical matching pursuit (HMP) is a popular feature learning method for RGB-D object recognition. However, the feature representation with only one dictionary for RGB channels in HMP does not capture sufficient visual information. In this paper, we propose multi-channel feature dictionaries based feature learning method for RGB-D object recognition. The process of feature extraction in the proposed method consists of two layers. The K-SVD algorithm is used to learn dictionaries in sparse coding of these two layers. In the first-layer, we obtain features by performing max pooling on sparse codes of pixels in a cell. And the obtained features of cells in a patch are concatenated to generate patch jointly features. Then, patch jointly features in the first-layer are used to learn the dictionary and sparse codes in the second-layer. Finally, spatial pyramid pooling can be applied to the patch jointly features of any layer to generate the final object features in our method. Experimental results show that our method with first or second-layer features can obtain a comparable or better performance than some published state-of-the-art methods.

Interlaminar and lateral excitatory amino acid connections in the striate cortex of monkey.

PubMed

Kisvarday, Z F; Cowey, A; Smith, A D; Somogyi, P

1989-02-01

The intrinsic excitatory amino acid pathways within the striate cortex of monkeys were studied by autoradiographic detection of retrogradely labeled somata following microinjections of D-3H-aspartate (D-3H-Asp) into different layers. The labeled amino acid was selectively accumulated by subpopulations of neurons and, to a small extent, by glial cells, the latter mainly in the supragranular layers. Immunocytochemical detection of neurons containing GABA showed that, apart from a few cells exclusively in layer I, GABAergic neurons do not accumulate D-3H-Asp. Several lines of evidence suggest that D-3H-Asp uptake occurred only at nerve terminals; thus, the pattern of perikaryal labeling allowed the delineation of interlaminar and lateral projections. Neurons in layer I probably project laterally, and layer I receives wide-ranging projections from layer IVB and layer V from cells up to 1300 microns laterally. Some neurons in layer II send a focused projection to lower layer VI. Some neurons in layers II/III project up to 1 mm laterally within their own layer, but relatively few neurons can be labeled in these projections. Similarly, in layers II/III few neurons can be retrogradely labeled from layers V and upper VI, and this projection is organized such that cells closer to the pia project deeper in layer V/VI. The connections of layer IVA could not be revealed separately because of the difficulty of confining injections to this thin sublamina. Neurons in layer IVB project up to 1300 microns within IVB itself. A small number of cells from IVB also project to layers III, IVC-alpha, V, and VI with much more restricted lateral spread. Neurons in upper IVC-alpha send axons to layer IVB with at least 600-800 microns lateral spread. Neurons in lower IVC-alpha/upper IVC-beta project to layer III with at least 300-500 microns lateral spread. The bottom 50-80 microns of layer IVC-beta contains neurons with a very focused projection, apparently exclusively to the layer III/IVA border region. Both layers IVC alpha and beta have rich connections within themselves, the beta sublayer having more restricted lateral connections. Some neurons in layer IVC-beta give a laterally restricted small input to layers IVC-alpha and IVB. Both IVC-alpha and -beta project to layers V and VI, and these projections are spread at least 400 microns laterally. Neurons in layer V project to all layers, but the projection to layers I-III and within layer V itself spread much further laterally than the projections to layers IV and VI.(ABSTRACT TRUNCATED AT 400 WORDS)

On the Development and Evolution of Astronomy in ancient Egypt

NASA Astrophysics Data System (ADS)

Maravelias, S. E.

In the present paper the development and evolution of astronomy in = Ancient Egypt are briefly examined. Emphasis is given to the = applications of astronomy on: (i) the orientation of temples and = pyramids, and the subsequent determination of the year; (ii) the = reorientation of temples --after the lapse of several centuries-- (due = to the fact that the priesthood was empirically aware of the precession = of equinoxes, and the subsequent use of this very fact in order to = estimate the archaeological age of temples, tombs and pyramids; (iii) = the heliacal rising of Sirius, which was used by ancient = priests-astronomers in order to fix the New Year's Day and determine the = seasons of the civil year, although the discre pancy of the Sothic cycle = in their calendrical system was not seriously taken into account. = Finally the conclusion put forward is that astronomy in Ancient Egypt = never reached the grounds of pure science (as in Ancient Greece), at = least before the Ptolemaic era, but always remained under the influence = of traditionalism and mythology pertaining more to the sphere of = religion and dogma.

Sunphotometry of the 2006-2007 aerosol optical/radiative properties at the Himalayan Nepal Climate Observatory-Pyramid (5079 m a.s.l.)

NASA Astrophysics Data System (ADS)

Gobbi, G. P.; Angelini, F.; Bonasoni, P.; Verza, G. P.; Marinoni, A.; Barnaba, F.

2010-11-01

In spite of being located at the heart of the highest mountain range in the world, the Himalayan Nepal Climate Observatory (5079 m a.s.l.) at the Ev-K2-CNR Pyramid is shown to be affected by the advection of pollution aerosols from the populated regions of southern Nepal and the Indo-Gangetic plains. Such an impact is observed along most of the period April 2006-March 2007 addressed here, with a minimum in the monsoon season. Backtrajectory-analysis indicates long-range transport episodes occurring in this year to originate mainly in the west Asian deserts. At this high altitude site, the measured aerosol optical depth is observed to be about one order of magnitude lower than the one measured at Ghandi College (60 m a.s.l.), in the Indo-Gangetic basin. As for Ghandi College, and in agreement with the in situ ground observations at the Pyramid, the fine mode aerosol optical depth maximizes during winter and minimizes in the monsoon season. Conversely, total optical depth maximizes during the monsoon due to the occurrence of elevated, coarse particle layers. Possible origins of these particles are wind erosion from the surrounding peaks and hydrated/cloud-processed aerosols. Assessment of the aerosol radiative forcing is then expected to be hampered by the presence of these high altitude particle layers, which impede an effective, continuous measurement of anthropogenic aerosol radiative properties from sky radiance inversions and/or ground measurements alone. Even though the retrieved absorption coefficients of pollution aerosols were rather large (single scattering albedo of the order of 0.6-0.9 were observed in the month of April 2006), the corresponding low optical depths (~0.03 at 500 nm) are expected to limit the relevant radiative forcing. Still, the high specific forcing of this aerosol and its capability of altering snow surface albedo provide good reasons for continuous monitoring.

Controlled Growth of Ordered III-Nitride Core-Shell Nanostructure Arrays for Visible Optoelectronic Devices

DOE PAGES

Rishinaramangalam, Ashwin K.; Mishkat Ul Masabih, Saadat; Fairchild, Michael N.; ...

2014-10-21

In our paper, we demonstrate the growth of ordered arrays of nonpolar {101 ¯ 0} core–shell nanowalls and semipolar {101 ¯ 1} core–shell pyramidal nanostripes on c-plane (0001) sapphire substrates using selective-area epitaxy and metal organic chemical vapor deposition. The nanostructure arrays are controllably patterned into LED mesa regions, demonstrating a technique to impart secondary lithography features into the arrays. Moreover, we study the dependence of the nanostructure cores on the epitaxial growth conditions and show that the geometry and morphology are strongly influenced by growth temperature, V/III ratio, and pulse interruption time. We also demonstrate the growth of InGaNmore » quantum well shells on the nanostructures and characterize the structures by using micro-photoluminescence and cross-section scanning tunneling electron microscopy.« less

Unitary IPSPs evoked by interneurons at the stratum radiatum-stratum lacunosum-moleculare border in the CA1 area of the rat hippocampus in vitro

PubMed Central

Vida, Imre; Halasy, Katalin; Szinyei, Csaba; Somogyi, Peter; Buhl, Eberhard H

1998-01-01

Hippocampal non-principal neurons at the stratum radiatum-stratum lacunosum-moleculare border (R-LM interneurons) of the CA1 area may constitute several cell classes and have been implicated in the generation of GABAergic unitary IPSPs. Using biocytin-filled electrodes we recorded R-LM interneurons intracellularly in vitro and determined their postsynaptic effects in concomitantly recorded pyramidal cells. Light microscopic analysis revealed four populations of R-LM interneurons with distinct axons: (1) basket cells (n= 4) with axons predominantly ramifying in the pyramidal cell layer; (2) Schaffer collateral/commissural pathway-associated interneurons (n= 10) stratifying in stratum radiatum and, to a lesser extent, stratum oriens; (3) perforant pathway-associated interneurons (n= 6) innervating the perforant path termination zone in stratum lacunosum-moleculare of the CA1 area as well as equivalent portions of the dentate gyrus and subiculum; and (4) neurogliaform interneurons (n= 2) characterized by their dense, compact axonal and dendritic arbour. Random electron microscopic sampling of synaptic targets revealed a preponderance of pyramidal neurons as postsynaptic elements. Basket cells had a synaptic target preference for somata and proximal dendrites, whereas the remainder of R-LM interneurons innervated dendritic shafts and spines. The axon of dendrite-targeting cells formed up to six putative contacts with individual postsynaptic pyramidal cells. Anatomically recovered R-LM interneurons (n= 22) had a mean resting membrane potential of -56.7 ± 3.6 mV, a membrane time constant of 12.9 ± 7.7 ms and an input resistance of 86.4 ± 29.2 MΩ. Depolarizing current pulses generally elicited overshooting action potentials (70.8 ± 6.9 mV) which had a mean duration, when measured at half-amplitude, of 0.7 ± 0.1 ms. In response to prolonged (> 200 ms) depolarizing current pulses all R-LM interneurons displayed (a varying degree of) spike frequency adaptation. Basket cells, Schaffer-associated and neurogliaform interneurons elicited small-amplitude (< 2 mV), short-latency IPSPs in postsynaptic pyramids (n= 5, 13 and 1, respectively). Those interactions in which an effect was elicited with the repetitive activation of the presynaptic neuron (n= 13) showed a substantial degree of postsynaptic response summation. Unitary IPSPs had fast kinetics and, whenever tested (n= 5; 1 basket cell and 4 Schaffer-associated interneurons), were abolished by the GABAA receptor antagonist bicuculline. Thus, R-LM interneurons comprise several distinct populations which evoke fast GABAA receptor-mediated IPSPs. The domain-specific innervation of postsynaptic pyramidal cells suggests functionally diverse effects on the integration of afferent information in functionally non-equivalent compartments of pyramidal cells. PMID:9503336

Loss of Either Rac1 or Rac3 GTPase Differentially Affects the Behavior of Mutant Mice and the Development of Functional GABAergic Networks

PubMed Central

Pennucci, Roberta; Talpo, Francesca; Astro, Veronica; Montinaro, Valentina; Morè, Lorenzo; Cursi, Marco; Castoldi, Valerio; Chiaretti, Sara; Bianchi, Veronica; Marenna, Silvia; Cambiaghi, Marco; Tonoli, Diletta; Leocani, Letizia; Biella, Gerardo; D'Adamo, Patrizia; de Curtis, Ivan

2016-01-01

Rac GTPases regulate the development of cortical/hippocampal GABAergic interneurons by affecting the early development and migration of GABAergic precursors. We have addressed the function of Rac1 and Rac3 proteins during the late maturation of hippocampal interneurons. We observed specific phenotypic differences between conditional Rac1 and full Rac3 knockout mice. Rac1 deletion caused greater generalized hyperactivity and cognitive impairment compared with Rac3 deletion. This phenotype matched with a more evident functional impairment of the inhibitory circuits in Rac1 mutants, showing higher excitability and reduced spontaneous inhibitory currents in the CA hippocampal pyramidal neurons. Morphological analysis confirmed a differential modification of the inhibitory circuits: deletion of either Rac caused a similar reduction of parvalbumin-positive inhibitory terminals in the pyramidal layer. Intriguingly, cannabinoid receptor-1-positive terminals were strongly increased only in the CA1 of Rac1-depleted mice. This increase may underlie the stronger electrophysiological defects in this mutant. Accordingly, incubation with an antagonist for cannabinoid receptors partially rescued the reduction of spontaneous inhibitory currents in the pyramidal cells of Rac1 mutants. Our results show that Rac1 and Rac3 have independent roles in the formation of GABAergic circuits, as highlighted by the differential effects of their deletion on the late maturation of specific populations of interneurons. PMID:26582364

Spectral, thermal, kinetic, molecular modeling and eukaryotic DNA degradation studies for a new series of albendazole (HABZ) complexes

NASA Astrophysics Data System (ADS)

El-Metwaly, Nashwa M.; Refat, Moamen S.

2011-01-01

This work represents the elaborated investigation for the ligational behavior of the albendazole ligand through its coordination with, Cu(II), Mn(II), Ni(II), Co(II) and Cr(III) ions. Elemental analysis, molar conductance, magnetic moment, spectral studies (IR, UV-Vis and ESR) and thermogravimetric analysis (TG and DTG) have been used to characterize the isolated complexes. A deliberate comparison for the IR spectra reveals that the ligand coordinated with all mentioned metal ions by the same manner as a neutral bidentate through carbonyl of ester moiety and NH groups. The proposed chelation form for such complexes is expected through out the preparation conditions in a relatively acidic medium. The powder XRD study reflects the amorphous nature for the investigated complexes except Mn(II). The conductivity measurements reflect the non-electrolytic feature for all complexes. In comparing with the constants for the magnetic measurements as well as the electronic spectral data, the octahedral structure was proposed strongly for Cr(III) and Ni(II), the tetrahedral for Co(II) and Mn(II) complexes but the square-pyramidal for the Cu(II) one. The thermogravimetric analysis confirms the presence or absence of water molecules by any type of attachments. Also, the kinetic parameters are estimated from DTG and TG curves. ESR spectrum data for Cu(II) solid complex confirms the square-pyramidal state is the most fitted one for the coordinated structure. The albendazole ligand and its complexes are biologically investigated against two bacteria as well as their effective effect on degradation of calf thymus DNA.

Postnatal Ablation of Synaptic Retinoic Acid Signaling Impairs Cortical Information Processing and Sensory Discrimination in Mice.

PubMed

Park, Esther; Tjia, Michelle; Zuo, Yi; Chen, Lu

2018-06-06

Retinoic acid (RA) and its receptors (RARs) are well established essential transcriptional regulators during embryonic development. Recent findings in cultured neurons identified an independent and critical post-transcriptional role of RA and RARα in the homeostatic regulation of excitatory and inhibitory synaptic transmission in mature neurons. However, the functional relevance of synaptic RA signaling in vivo has not been established. Here, using somatosensory cortex as a model system and the RARα conditional knock-out mouse as a tool, we applied multiple genetic manipulations to delete RARα postnatally in specific populations of cortical neurons, and asked whether synaptic RA signaling observed in cultured neurons is involved in cortical information processing in vivo Indeed, conditional ablation of RARα in mice via a CaMKIIα-Cre or a layer 5-Cre driver line or via somatosensory cortex-specific viral expression of Cre-recombinase impaired whisker-dependent texture discrimination, suggesting a critical requirement of RARα expression in L5 pyramidal neurons of somatosensory cortex for normal tactile sensory processing. Transcranial two-photon imaging revealed a significant increase in dendritic spine elimination on apical dendrites of somatosensory cortical layer 5 pyramidal neurons in these mice. Interestingly, the enhancement of spine elimination is whisker experience-dependent as whisker trimming rescued the spine elimination phenotype. Additionally, experiencing an enriched environment improved texture discrimination in RARα-deficient mice and reduced excessive spine pruning. Thus, RA signaling is essential for normal experience-dependent cortical circuit remodeling and sensory processing. SIGNIFICANCE STATEMENT The importance of synaptic RA signaling has been demonstrated in in vitro studies. However, whether RA signaling mediated by RARα contributes to neural circuit functions in vivo remains largely unknown. In this study, using a RARα conditional knock-out mouse, we performed multiple regional/cell-type-specific manipulation of RARα expression in the postnatal brain, and show that RARα signaling contributes to normal whisker-dependent texture discrimination as well as regulating spine dynamics of apical dendrites from layer (L5) pyramidal neurons in S1. Deletion of RARα in excitatory neurons in the forebrain induces elevated spine elimination and impaired sensory discrimination. Our study provides novel insights into the role of RARα signaling in cortical processing and experience-dependent spine maturation. Copyright © 2018 the authors 0270-6474/18/385277-12$15.00/0.

Centre of pressure correlates with pyramid performance in acrobatic gymnastics.

PubMed

Floría, Pablo; Gómez-Landero, Luis Arturo; Harrison, Andrew J

2015-01-01

Acrobatic gymnasts need excellent balance control to execute pyramids where one gymnast is supported by another. The objectives of this study were: (1) to describe balance performance by assessing the centre of pressure displacement in a group of acrobatic gymnasts executing pyramids; (2) to determine the relationship between the parameters describing the centre of pressure oscillations and pyramid score; and (3) to examine the role of each foot in providing a solid base of support to maintain the balance of the pyramid. Sixteen acrobatic gymnasts grouped in pairs performed a Half pyramid and a Straddle pyramid held for 7 s on two force platforms. Path length, variance, range trajectory, and surface area of the centre of pressure of each foot were examined to analyse the balance of the pyramid. The path length was correlated with the pyramid score (Straddle: p = 0.692 [large]; Half: p = 0.407 [moderate]). There were differences in the functions of each leg to maintain balance, with the non-preferred leg supporting a higher weight of the pyramid while the preferred leg performed control movements to maintain balance. The results suggested that quantitative analysis of balance can provide important information on pyramid performance.

Calibrating the interaction matrix for the LINC-NIRVANA high layer wavefront sensor.

PubMed

Zhang, Xianyu; Arcidiacono, Carmelo; Conrad, Albert R; Herbst, Thomas M; Gaessler, Wolfgang; Bertram, Thomas; Ragazzoni, Roberto; Schreiber, Laura; Diolaiti, Emiliano; Kuerster, Martin; Bizenberger, Peter; Meschke, Daniel; Rix, Hans-Walter; Rao, Changhui; Mohr, Lars; Briegel, Florian; Kittmann, Frank; Berwein, Juergen; Trowitzsch, Jan

2012-03-26

LINC-NIRVANA is a near-infrared Fizeau interferometric imager that will operate at the Large Binocular Telescope. In preparation for the commissioning of this instrument, we conducted experiments for calibrating the high-layer wavefront sensor of the layer-oriented multi-conjugate adaptive optics system. For calibrating the multi-pyramid wavefront sensor, four light sources were used to simulate guide stars. Using this setup, we developed the push-pull method for calibrating the interaction matrix. The benefits of this method over the traditional push-only method are quantified, and also the effects of varying the number of push-pull frames over which aberrations are averaged is reported. Finally, we discuss a method for measuring mis-conjugation between the deformable mirror and the wavefront sensor, and the proper positioning of the wavefront sensor detector with respect to the four pupil positions.

All-optical mapping of barrel cortex circuits based on simultaneous voltage-sensitive dye imaging and channelrhodopsin-mediated photostimulation

PubMed Central

Lo, Shun Qiang; Koh, Dawn X. P.; Sng, Judy C. G.; Augustine, George J.

2015-01-01

Abstract. We describe an experimental approach that uses light to both control and detect neuronal activity in mouse barrel cortex slices: blue light patterned by a digital micromirror array system allowed us to photostimulate specific layers and columns, while a red-shifted voltage-sensitive dye was used to map out large-scale circuit activity. We demonstrate that such all-optical mapping can interrogate various circuits in somatosensory cortex by sequentially activating different layers and columns. Further, mapping in slices from whisker-deprived mice demonstrated that chronic sensory deprivation did not significantly alter feedforward inhibition driven by layer 5 pyramidal neurons. Further development of voltage-sensitive optical probes should allow this all-optical mapping approach to become an important and high-throughput tool for mapping circuit interactions in the brain. PMID:26158003

Synthesis, properties and applications of 2D layered MIIIXVI (M = Ga, In; X = S, Se, Te) materials.

PubMed

Xu, Kai; Yin, Lei; Huang, Yun; Shifa, Tofik Ahmed; Chu, Junwei; Wang, Feng; Cheng, Ruiqing; Wang, Zhenxing; He, Jun

2016-09-29

Group III-VI compounds M III X VI (M = Ga, In; X = S, Se, Te) are one class of important 2D layered materials and are currently attracting increasing interest due to their unique electronic and optoelectronic properties and their great potential applications in various other fields. Similar to 2D layered transition metal dichalcogenides (TMDs), M III X VI also have the significant merits of ultrathin thickness, ultrahigh surface-to-volume ratio, and high compatibility with flexible devices. More impressively, in contrast with TMDCs, M III X VI demonstrate many superior properties, such as direct band gap electronic structure, high carrier mobility, rare p-type electronic behaviors, high charge density, and so on. These unique characteristics cause high-performance device applications in electronics, optoelectronics, and optics. In this review, we aim to provide a summary of the state-of-the-art of research activities in 2D layered M III X VI materials. The scope of the review covers the synthesis and properties of 2D layered M III X VI materials and their van der Waals heterostructures. We especially focus on the applications in electronics and optoelectronics. Moreover, the review concludes with some perspectives on future developments in this field.

Low Temperature Grown and Highly Non-Stoichiometric GaAs and Related Materials

DTIC Science & Technology

1994-08-03

Ser. No. 67 (1983), p. 285.attributed to the nonuniformity of crystal growth 2T. Figielski, T. Wonsinski and A. Mokosa, Phys. Stat. Solidi (a) condition...1.75 pyramidal defect distribution was nonuniform in this pm; sample C, 1.6 pm; and sample D, 0.95 prm. Each sample, the defects being separated...the layers grown on [0011 oriented substrates whereas growth on the near [1101 substrates resulted in compositional nonuniformities , macrosteps for

Chronic In Vivo Imaging Shows No Evidence of Dendritic Plasticity or Functional Remapping in the Contralesional Cortex after Stroke

PubMed Central

Johnston, David G.; Denizet, Marie; Mostany, Ricardo

2013-01-01

Most stroke survivors exhibit a partial recovery from their deficits. This presumably occurs because of remapping of lost capabilities to functionally related brain areas. Functional brain imaging studies suggest that remapping in the contralateral uninjured cortex might represent a transient stage of compensatory plasticity. Some postmortem studies have also shown that cortical lesions, including stroke, can trigger dendritic plasticity in the contralateral hemisphere, but the data are controversial. We used longitudinal in vivo two-photon microscopy in the contralateral homotopic cortex to record changes in dendritic spines of layer 5 pyramidal neurons in green fluorescent protein mice. We could not detect de novo growth of dendrites or changes in the density or turnover of spines for up to 4 weeks after stroke. We also used intrinsic optical signal imaging to investigate whether the forepaw (FP) sensory representation is remapped to the spared homotopic cortex after stroke. Stimulation of the contralateral FP reliably produced strong intrinsic signals in the spared hemisphere, but we could never detect a signal with ipsilateral FP stimulation after stroke. This lack of contralateral plasticity at the level of apical dendrites of layer 5 pyramidal neurons and FP sensory maps suggests that the contralesional cortex may not contribute to functional recovery after stroke and that, at least in mice, the peri-infarct cortex plays the dominant role in postischemic plasticity. PMID:22499800

Chronic in vivo imaging shows no evidence of dendritic plasticity or functional remapping in the contralesional cortex after stroke.

PubMed

Johnston, David G; Denizet, Marie; Mostany, Ricardo; Portera-Cailliau, Carlos

2013-04-01

Most stroke survivors exhibit a partial recovery from their deficits. This presumably occurs because of remapping of lost capabilities to functionally related brain areas. Functional brain imaging studies suggest that remapping in the contralateral uninjured cortex might represent a transient stage of compensatory plasticity. Some postmortem studies have also shown that cortical lesions, including stroke, can trigger dendritic plasticity in the contralateral hemisphere, but the data are controversial. We used longitudinal in vivo two-photon microscopy in the contralateral homotopic cortex to record changes in dendritic spines of layer 5 pyramidal neurons in green fluorescent protein mice. We could not detect de novo growth of dendrites or changes in the density or turnover of spines for up to 4 weeks after stroke. We also used intrinsic optical signal imaging to investigate whether the forepaw (FP) sensory representation is remapped to the spared homotopic cortex after stroke. Stimulation of the contralateral FP reliably produced strong intrinsic signals in the spared hemisphere, but we could never detect a signal with ipsilateral FP stimulation after stroke. This lack of contralateral plasticity at the level of apical dendrites of layer 5 pyramidal neurons and FP sensory maps suggests that the contralesional cortex may not contribute to functional recovery after stroke and that, at least in mice, the peri-infarct cortex plays the dominant role in postischemic plasticity.

Nop2 is expressed during proliferation of neural stem cells and in adult mouse and human brain.

PubMed

Kosi, Nina; Alić, Ivan; Kolačević, Matea; Vrsaljko, Nina; Jovanov Milošević, Nataša; Sobol, Margarita; Philimonenko, Anatoly; Hozák, Pavel; Gajović, Srećko; Pochet, Roland; Mitrečić, Dinko

2015-02-09

The nucleolar protein 2 gene encodes a protein specific for the nucleolus. It is assumed that it plays a role in the synthesis of ribosomes and regulation of the cell cycle. Due to its link to cell proliferation, higher expression of Nop2 indicates a worse tumor prognosis. In this work we used Nop2(gt1gaj) gene trap mouse strain. While lethality of homozygous animals suggested a vital role of this gene, heterozygous animals allowed the detection of expression of Nop2 in various tissues, including mouse brain. Histochemistry, immunohistochemistry and immunoelectron microscopy techniques, applied to a mature mouse brain, human brain and on mouse neural stem cells revealed expression of Nop2 in differentiating cells, including astrocytes, as well as in mature neurons. Nop2 was detected in various regions of mouse and human brain, mostly in large pyramidal neurons. In the human, Nop2 was strongly expressed in supragranular and infragranular layers of the somatosensory cortex and in layer III of the cingulate cortex. Also, Nop2 was detected in CA1 and the subiculum of the hippocampus. Subcellular analyses revealed predominant location of Nop2 within the dense fibrillar component of the nucleolus. To test if Nop2 expression correlates to cell proliferation occurring during tissue regeneration, we induced strokes in mice by middle cerebral artery occlusion. Two weeks after stroke, the number of Nop2/nestin double positive cells in the region affected by ischemia and the periventricular zone substantially increased. Our findings suggest a newly discovered role of Nop2 in both mature neurons and in cells possibly involved in the regeneration of nervous tissue. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Advanced light-scattering materials: Double-textured ZnO:B films grown by LP-MOCVD

NASA Astrophysics Data System (ADS)

Addonizio, M. L.; Spadoni, A.; Antonaia, A.

2013-12-01

Double-textured ZnO:B layers with enhanced optical scattering in both short and long wavelength regions have been successfully fabricated using MOCVD technique through a three step process. Growth of double-textured structures has been induced by wet etching on polycrystalline ZnO surface. Our double-layer structure consists of a first ZnO:B layer wet etched and subsequently used as substrate for a second ZnO:B layer deposition. Polycrystalline ZnO:B layers were etched by utilizing diluted solutions of fluoridic acid (HF), chloridric acid (HCl) and phosphoric acid (H3PO4) and their effect on surface morphology modification was systematically investigated. The morphology of the second deposited ZnO layer strongly depended on the surface properties of the etched ZnO first layer. Growth of cauliflower-like texture was induced by protrusions presence on the HCl etched surface. Optimized double-layer structure shows a cauliflower-like double texture with higher RMS roughness and increased spectral haze values in both short and long wavelength regions, compared to conventional pyramidal-like single texture. Furthermore, this highly scattering structure preserves excellent optical and electrical properties.

Combining diffusion magnetic resonance tractography with stereology highlights increased cross-cortical integration in primates.

PubMed

Charvet, Christine J; Hof, Patrick R; Raghanti, Mary Ann; Van Der Kouwe, Andre J; Sherwood, Chet C; Takahashi, Emi

2017-04-01

The isocortex of primates is disproportionately expanded relative to many other mammals, yet little is known about what the expansion of the isocortex entails for differences in cellular composition and connectivity patterns in primates. Across the depth of the isocortex, neurons exhibit stereotypical patterns of projections. Upper-layer neurons (i.e., layers II-IV) project within and across cortical areas, whereas many lower-layer pyramidal neurons (i.e., layers V-VI) favor connections to subcortical regions. To identify evolutionary changes in connectivity patterns, we quantified upper (i.e., layers II-IV)- and lower (i.e., layers V-VI)-layer neuron numbers in primates and other mammals such as rodents and carnivores. We also used MR tractography based on high-angular resolution diffusion imaging and diffusion spectrum imaging to compare anterior-to-posterior corticocortical tracts between primates and other mammals. We found that primates possess disproportionately more upper-layer neurons as well as an expansion of anterior-to-posterior corticocortical tracts compared with other mammals. Taken together, these findings demonstrate that primates deviate from other mammals in exhibiting increased cross-cortical connectivity. J. Comp. Neurol. 525:1075-1093, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Monolithically Integrated μLEDs on Silicon Neural Probes for High-Resolution Optogenetic Studies in Behaving Animals

PubMed Central

Wu, Fan; Stark, Eran; Ku, Pei-Cheng; Wise, Kensall D.; Buzsáki, György; Yoon, Euisik

2015-01-01

SUMMARY We report a scalable method to monolithically integrate microscopic light emitting diodes (μLEDs) and recording sites onto silicon neural probes for optogenetic applications in neuroscience. Each μLED and recording site has dimensions similar to a pyramidal neuron soma, providing confined emission and electrophysiological recording of action potentials and local field activity. We fabricated and implanted the four-shank probes, each integrated with 12 μLEDs and 32 recording sites, into the CA1 pyramidal layer of anesthetized and freely moving mice. Spikes were robustly induced by 60 nW light power, and fast population oscillations were induced at the microwatt range. To demonstrate the spatiotemporal precision of parallel stimulation and recording, we achieved independent control of distinct cells ~50 μm apart and of differential somatodendritic compartments of single neurons. The scalability and spatiotemporal resolution of this monolithic optogenetic tool provides versatility and precision for cellular-level circuit analysis in deep structures of intact, freely moving animals. PMID:26627311

Different patterns of motor activity induce differential plastic changes in pyramidal neurons in the motor cortex of rats: A Golgi study.

PubMed

Vázquez-Hernández, Nallely; González-Tapia, Diana C; Martínez-Torres, Nestor I; González-Tapia, David; González-Burgos, Ignacio

2017-09-14

Rehabilitation is a process which favors recovery after brain damage involving motor systems, and neural plasticity is the only real resource the brain has for inducing neurobiological events in order to bring about re-adaptation. Rats were placed on a treadmill and made to walk, in different groups, at different velocities and with varying degrees of inclination. Plastic changes in the spines of the apical and basal dendrites of fifth-layer pyramidal neurons in the motor cortices of the rats were detected after study with the Golgi method. Numbers of dendritic spines increased in the three experimental groups, and thin, mushroom, stubby, wide, and branched spines increased or decreased in proportion depending on the motor demands made of each group. Along with the numerical increase of spines, the present findings provide evidence that dendritic spines' geometrical plasticity is involved in the differential performance of motor activity. Copyright © 2017 Elsevier B.V. All rights reserved.

Crystal structure and crystal chemistry of melanovanadite, a natural vanadium bronze.

USGS Publications Warehouse

Konnert, J.A.; Evans, H.T.

1987-01-01

The crystal structure of melanovanadite from Minas Ragra, Peru, has been determined in space group P1. The triclinic unit cell (non-standard) has a 6.360(2), b 18.090(9), c 6.276(2) A, alpha 110.18(4)o, beta 101.62(3)o, gamma 82.86(4)o. A subcell with b' = b/2 was found by crystal-structure analysis to contain CaV4O10.5H2O. The subcell has a layer structure in which the vanadate sheet consists of corner-shared tetrahedral VO4 and double square-pyramidal V2O8 groups, similar to that previously found in synthetic CsV2O5. Refinement of the full structure (R = 0.056) showed that the Ca atom, which half-occupies a general position in the subcell, is 90% ordered at one of these sites in the whole unit cell. Bond length-bond strength estimates indicate that the tetrahedra contain V5+, and the square pyramids, V4+.-J.A.Z.

Irregular spiking of pyramidal neurons organizes as scale-invariant neuronal avalanches in the awake state

PubMed Central

Bellay, Timothy; Klaus, Andreas; Seshadri, Saurav; Plenz, Dietmar

2015-01-01

Spontaneous fluctuations in neuronal activity emerge at many spatial and temporal scales in cortex. Population measures found these fluctuations to organize as scale-invariant neuronal avalanches, suggesting cortical dynamics to be critical. Macroscopic dynamics, though, depend on physiological states and are ambiguous as to their cellular composition, spatiotemporal origin, and contributions from synaptic input or action potential (AP) output. Here, we study spontaneous firing in pyramidal neurons (PNs) from rat superficial cortical layers in vivo and in vitro using 2-photon imaging. As the animal transitions from the anesthetized to awake state, spontaneous single neuron firing increases in irregularity and assembles into scale-invariant avalanches at the group level. In vitro spike avalanches emerged naturally yet required balanced excitation and inhibition. This demonstrates that neuronal avalanches are linked to the global physiological state of wakefulness and that cortical resting activity organizes as avalanches from firing of local PN groups to global population activity. DOI: http://dx.doi.org/10.7554/eLife.07224.001 PMID:26151674

Long term potentiation, but not depression, in interlamellar hippocampus CA1.

PubMed

Sun, Duk-Gyu; Kang, Hyeri; Tetteh, Hannah; Su, Junfeng; Lee, Jihwan; Park, Sung-Won; He, Jufang; Jo, Jihoon; Yang, Sungchil; Yang, Sunggu

2018-03-26

Synaptic plasticity in the lamellar CA3 to CA1 circuitry has been extensively studied while interlamellar CA1 to CA1 connections have not yet received much attention. One of our earlier studies demonstrated that axons of CA1 pyramidal neurons project to neighboring CA1 neurons, implicating information transfer along a longitudinal interlamellar network. Still, it remains unclear whether long-term synaptic plasticity is present within this longitudinal CA1 network. Here, we investigate long-term synaptic plasticity between CA1 pyramidal cells, using in vitro and in vivo extracellular recordings and 3D holography glutamate uncaging. We found that the CA1-CA1 network exhibits NMDA receptor-dependent long-term potentiation (LTP) without direction or layer selectivity. By contrast, we find no significant long-term depression (LTD) under various LTD induction protocols. These results implicate unique synaptic properties in the longitudinal projection suggesting that the interlamellar CA1 network could be a promising structure for hippocampus-related information processing and brain diseases.

Unique membrane properties and enhanced signal processing in human neocortical neurons.

PubMed

Eyal, Guy; Verhoog, Matthijs B; Testa-Silva, Guilherme; Deitcher, Yair; Lodder, Johannes C; Benavides-Piccione, Ruth; Morales, Juan; DeFelipe, Javier; de Kock, Christiaan Pj; Mansvelder, Huibert D; Segev, Idan

2016-10-06

The advanced cognitive capabilities of the human brain are often attributed to our recently evolved neocortex. However, it is not known whether the basic building blocks of the human neocortex, the pyramidal neurons, possess unique biophysical properties that might impact on cortical computations. Here we show that layer 2/3 pyramidal neurons from human temporal cortex (HL2/3 PCs) have a specific membrane capacitance ( C m ) of ~0.5 µF/cm 2 , half of the commonly accepted 'universal' value (~1 µF/cm 2 ) for biological membranes. This finding was predicted by fitting in vitro voltage transients to theoretical transients then validated by direct measurement of C m in nucleated patch experiments. Models of 3D reconstructed HL2/3 PCs demonstrated that such low C m value significantly enhances both synaptic charge-transfer from dendrites to soma and spike propagation along the axon. This is the first demonstration that human cortical neurons have distinctive membrane properties, suggesting important implications for signal processing in human neocortex.

Three Types of Cortical L5 Neurons that Differ in Brain-Wide Connectivity and Function

PubMed Central

Kim, Euiseok J.; Juavinett, Ashley L.; Kyubwa, Espoir M.; Jacobs, Matthew W.; Callaway, Edward M.

2015-01-01

SUMMARY Cortical layer 5 (L5) pyramidal neurons integrate inputs from many sources and distribute outputs to cortical and subcortical structures. Previous studies demonstrate two L5 pyramid types: cortico-cortical (CC) and cortico-subcortical (CS). We characterize connectivity and function of these cell types in mouse primary visual cortex and reveal a new subtype. Unlike previously described L5 CC and CS neurons, this new subtype does not project to striatum [cortico-cortical, non-striatal (CC-NS)] and has distinct morphology, physiology and visual responses. Monosynaptic rabies tracing reveals that CC neurons preferentially receive input from higher visual areas, while CS neurons receive more input from structures implicated in top-down modulation of brain states. CS neurons are also more direction-selective and prefer faster stimuli than CC neurons. These differences suggest distinct roles as specialized output channels, with CS neurons integrating information and generating responses more relevant to movement control and CC neurons being more important in visual perception. PMID:26671462

Selective layer disordering in III-nitrides with a capping layer

DOEpatents

Wierer, Jr., Jonathan J.; Allerman, Andrew A.

2016-06-14

Selective layer disordering in a doped III-nitride superlattice can be achieved by depositing a dielectric capping layer on a portion of the surface of the superlattice and annealing the superlattice to induce disorder of the layer interfaces under the uncapped portion and suppress disorder of the interfaces under the capped portion. The method can be used to create devices, such as optical waveguides, light-emitting diodes, photodetectors, solar cells, modulators, laser, and amplifiers.

Neuronal density, size and shape in the human anterior cingulate cortex: a comparison of Nissl and NeuN staining.

PubMed

Gittins, Rebecca; Harrison, Paul J

2004-03-15

There are an increasing number of quantitative morphometric studies of the human cerebral cortex, especially as part of comparative investigations of major psychiatric disorders. In this context, the present study had two aims. First, to provide quantitative data regarding key neuronal morphometric parameters in the anterior cingulate cortex. Second, to compare the results of conventional Nissl staining with those observed after immunostaining with NeuN, an antibody becoming widely used as a selective neuronal marker. We stained adjacent sections of area 24b from 16 adult brains with cresyl violet or NeuN. We measured the density of pyramidal and non-pyramidal neurons, and the size and shape of pyramidal neurons, in laminae II, III, Va, Vb and VI, using two-dimensional counting methods. Strong correlations between the two modes of staining were seen for all variables. However, NeuN gave slightly higher estimates of neuronal density and size, and a more circular perikaryal shape. Brain pH was correlated with neuronal size, measured with both methods, and with neuronal shape. Age and post-mortem interval showed no correlations with any parameter. These data confirm the value of NeuN as a tool for quantitative neuronal morphometric studies in routinely processed human brain tissue. Absolute values are highly correlated between NeuN and cresyl violet stains, but cannot be interchanged. NeuN may be particularly useful when it is important to distinguish small neurons from glia, such as in cytoarchitectural studies of the cerebral cortex in depression and schizophrenia.

Method to grow group III-nitrides on copper using passivation layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Qiming; Wang, George T; Figiel, Jeffrey T

Group III-nitride epilayers can be grown directly on copper substrates using intermediate passivation layers. For example, single crystalline c-plane GaN can be grown on Cu (110) substrates with MOCVD. The growth relies on a low temperature AlN passivation layer to isolate any alloying reaction between Ga and Cu.

Neuroelectric Tuning of Cortical Oscillations by Apical Dendrites in Loop Circuits

PubMed Central

LaBerge, David; Kasevich, Ray S.

2017-01-01

Bundles of relatively long apical dendrites dominate the neurons that make up the thickness of the cerebral cortex. It is proposed that a major function of the apical dendrite is to produce sustained oscillations at a specific frequency that can serve as a common timing unit for the processing of information in circuits connected to that apical dendrite. Many layer 5 and 6 pyramidal neurons are connected to thalamic neurons in loop circuits. A model of the apical dendrites of these pyramidal neurons has been used to simulate the electric activity of the apical dendrite. The results of that simulation demonstrated that subthreshold electric pulses in these apical dendrites can be tuned to specific frequencies and also can be fine-tuned to narrow bandwidths of less than one Hertz (1 Hz). Synchronous pulse outputs from the circuit loops containing apical dendrites can tune subthreshold membrane oscillations of neurons they contact. When the pulse outputs are finely tuned, they function as a local “clock,” which enables the contacted neurons to synchronously communicate with each other. Thus, a shared tuning frequency can select neurons for membership in a circuit. Unlike layer 6 apical dendrites, layer 5 apical dendrites can produce burst firing in many of their neurons, which increases the amplitude of signals in the neurons they contact. This difference in amplitude of signals serves as basis of selecting a sub-circuit for specialized processing (e.g., sustained attention) within the typically larger layer 6-based circuit. After examining the sustaining of oscillations in loop circuits and the processing of spikes in network circuits, we propose that cortical functioning can be globally viewed as two systems: a loop system and a network system. The loop system oscillations influence the network system’s timing and amplitude of pulse signals, both of which can select circuits that are momentarily dominant in cortical activity. PMID:28659768

Neuroelectric Tuning of Cortical Oscillations by Apical Dendrites in Loop Circuits.

PubMed

LaBerge, David; Kasevich, Ray S

2017-01-01

Bundles of relatively long apical dendrites dominate the neurons that make up the thickness of the cerebral cortex. It is proposed that a major function of the apical dendrite is to produce sustained oscillations at a specific frequency that can serve as a common timing unit for the processing of information in circuits connected to that apical dendrite. Many layer 5 and 6 pyramidal neurons are connected to thalamic neurons in loop circuits. A model of the apical dendrites of these pyramidal neurons has been used to simulate the electric activity of the apical dendrite. The results of that simulation demonstrated that subthreshold electric pulses in these apical dendrites can be tuned to specific frequencies and also can be fine-tuned to narrow bandwidths of less than one Hertz (1 Hz). Synchronous pulse outputs from the circuit loops containing apical dendrites can tune subthreshold membrane oscillations of neurons they contact. When the pulse outputs are finely tuned, they function as a local "clock," which enables the contacted neurons to synchronously communicate with each other. Thus, a shared tuning frequency can select neurons for membership in a circuit. Unlike layer 6 apical dendrites, layer 5 apical dendrites can produce burst firing in many of their neurons, which increases the amplitude of signals in the neurons they contact. This difference in amplitude of signals serves as basis of selecting a sub-circuit for specialized processing (e.g., sustained attention) within the typically larger layer 6-based circuit. After examining the sustaining of oscillations in loop circuits and the processing of spikes in network circuits, we propose that cortical functioning can be globally viewed as two systems: a loop system and a network system. The loop system oscillations influence the network system's timing and amplitude of pulse signals, both of which can select circuits that are momentarily dominant in cortical activity.

Effect of prenatal exposure to ethanol on the ultrastructure of layer V of mature rat somatosensory cortex.

PubMed

al-Rabiai, S; Miller, M W

1989-12-01

Recent data have shown that the structure and function of layer V pyramidal neurons, e.g. corticospinal neurons, is altered by prenatal exposure to ethanol. We examined the effect of ethanol on the ultrastructure of layer V in somatosensory cortex. Timed pregnant rats were fed a diet containing 6.7% (v/v) ethanol (E) or pair-fed a nutritionally matched control diet (C). Thirty-day-old offspring of these mothers were prepared by standard electron microscopic techniques. The somata of pyramidal and local circuit neurons and the neuropil were analysed. Prenatal exposure to ethanol induced alterations in the somata of both populations of neurons. The parallel stacking of cisternae characteristic of C-treated rats was disorganized in E-treated rats. Moreover, the Golgi complex and lysosomes occupied a larger fraction of the somata of E-treated rats. The number and frequency of symmetric axosomatic synapses, but not asymmetric axosomatic synapses, formed by both types of neurons were significantly greater in E-treated rats. Gestational exposure to ethanol produced a variety of changes in the neuropil. Dendrites, particularly dendritic shafts, occupied less space in E-treated rats. In contrast, axons accounted for significantly more of the neuropil in E-treated rats than in controls. This increase in axonal space was due to a significantly greater coverage by non-myelinated axons and a significantly smaller coverage by myelinated axons in E-treated rats than in C-treated rats. Although the overall frequency of synapses was similar in both treatment groups, there were significantly more asymmetric synapses in E-treated rats, and most of these were axospinous synapses. These differences may contribute to documented physiological changes such as the lower rate of glucose utilization in layer V of somatosensory cortex of E-treated rats and they may underlie the mental retardation which is characteristic of children with foetal alcohol syndrome.

Cell Class-Dependent Intracortical Connectivity and Output Dynamics of Layer 6 Projection Neurons of the Rat Primary Visual Cortex.

PubMed

Cotel, Florence; Fletcher, Lee N; Kalita-de Croft, Simon; Apergis-Schoute, John; Williams, Stephen R

2018-07-01

Neocortical information processing is powerfully influenced by the activity of layer 6 projection neurons through control of local intracortical and subcortical circuitry. Morphologically distinct classes of layer 6 projection neuron have been identified in the mammalian visual cortex, which exhibit contrasting receptive field properties, but little information is available on their functional specificity. To address this we combined anatomical tracing techniques with high-resolution patch-clamp recording to identify morphological and functional distinct classes of layer 6 projection neurons in the rat primary visual cortex, which innervated separable subcortical territories. Multisite whole-cell recordings in brain slices revealed that corticoclaustral and corticothalamic layer 6 projection neurons exhibited similar somatically recorded electrophysiological properties. These classes of layer 6 projection neurons were sparsely and reciprocally synaptically interconnected, but could be differentiated by cell-class, but not target-cell-dependent rules of use-dependent depression and facilitation of unitary excitatory synaptic output. Corticoclaustral and corticothalamic layer 6 projection neurons were differentially innervated by columnar excitatory circuitry, with corticoclaustral, but not corticothalamic, neurons powerfully driven by layer 4 pyramidal neurons, and long-range pathways conveyed in neocortical layer 1. Our results therefore reveal projection target-specific, functionally distinct, streams of layer 6 output in the rodent neocortex.

Cortical modulation of auditory processing in the midbrain

PubMed Central

Bajo, Victoria M.; King, Andrew J.

2013-01-01

In addition to their ascending pathways that originate at the receptor cells, all sensory systems are characterized by extensive descending projections. Although the size of these connections often outweighs those that carry information in the ascending auditory pathway, we still have a relatively poor understanding of the role they play in sensory processing. In the auditory system one of the main corticofugal projections links layer V pyramidal neurons with the inferior colliculus (IC) in the midbrain. All auditory cortical fields contribute to this projection, with the primary areas providing the largest outputs to the IC. In addition to medium and large pyramidal cells in layer V, a variety of cell types in layer VI make a small contribution to the ipsilateral corticocollicular projection. Cortical neurons innervate the three IC subdivisions bilaterally, although the contralateral projection is relatively small. The dorsal and lateral cortices of the IC are the principal targets of corticocollicular axons, but input to the central nucleus has also been described in some studies and is distinctive in its laminar topographic organization. Focal electrical stimulation and inactivation studies have shown that the auditory cortex can modify almost every aspect of the response properties of IC neurons, including their sensitivity to sound frequency, intensity, and location. Along with other descending pathways in the auditory system, the corticocollicular projection appears to continually modulate the processing of acoustical signals at subcortical levels. In particular, there is growing evidence that these circuits play a critical role in the plasticity of neural processing that underlies the effects of learning and experience on auditory perception by enabling changes in cortical response properties to spread to subcortical nuclei. PMID:23316140

Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Kim, Jeomoh; Ji, Mi-Hee; Detchprohm, Theeradetch; Dupuis, Russell D.; Fischer, Alec M.; Ponce, Fernando A.; Ryou, Jae-Hyun

2015-09-01

Unintentional incorporation of gallium (Ga) in InAlN layers grown with different molar flow rates of Group-III precursors by metalorganic chemical vapor deposition has been experimentally investigated. The Ga mole fraction in the InAl(Ga)N layer was increased significantly with the trimethylindium (TMIn) flow rate, while the trimethylaluminum flow rate controls the Al mole fraction. The evaporation of metallic Ga from the liquid phase eutectic system between the pyrolized In from injected TMIn and pre-deposited metallic Ga was responsible for the Ga auto-incorporation into the InAl(Ga)N layer. The theoretical calculation on the equilibrium vapor pressure of liquid phase Ga and the effective partial pressure of Group-III precursors based on growth parameters used in this study confirms the influence of Group-III precursors on Ga auto-incorporation. More Ga atoms can be evaporated from the liquid phase Ga on the surrounding surfaces in the growth chamber and then significant Ga auto-incorporation can occur due to the high equilibrium vapor pressure of Ga comparable to effective partial pressure of input Group-III precursors during the growth of InAl(Ga)N layer.

Isotopic Evidence for Early Trade in Animals between Old Kingdom Egypt and Canaan

PubMed Central

Greenfield, Haskel J.; Shai, Itzhaq; Babcock, Lindsay E.; Maeir, Aren M.

2016-01-01

Isotope data from a sacrificial ass and several ovicaprines (sheep/goat) from Early Bronze Age household deposits at Tell es-Safi/Gath, Israel provide direct evidence for the movement of domestic draught/draft and husbandry animals between Old Kingdom Egypt (during the time of the Pyramids) and Early Bronze Age III Canaan (ca. 2900–2500 BCE). Vacillating, bi-directional connections between Egypt and Canaan are known throughout the Early Bronze Age, but here we provide the first concrete evidence of early trade in animals from Egypt to Canaan. PMID:27322197

Layered double hydroxide stability. 1. Relative stabilities of layered double hydroxides and their simple counterparts

NASA Technical Reports Server (NTRS)

Boclair, J. W.; Braterman, P. S.

1999-01-01

Solutions containing di- and trivalent metal chlorides [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+; M(III) = Al3+, Fe3+] were titrated with NaOH to yield hydrotalcite-like layered double hydroxides (LDH), [[M(II)]1-x[M(III)]x(OH)2][Cl]x yH2O, by way of M(III) hydroxide/hydrous oxide intermediates. Analysis of the resultant titration curves yields nominal solubility constants for the LDH. The corresponding LDH stabilities are in the order Mg < Mn < Co approximately Ni < Zn for M(II) and Al < Fe for M(III). The stability of LDH relative to the separate metal hydroxides/hydrous oxides is discussed.

Molecular modelling, spectroscopic characterization and biological studies of tetraazamacrocyclic metal complexes

NASA Astrophysics Data System (ADS)

Rathi, Parveen; Sharma, Kavita; Singh, Dharam Pal

2014-09-01

Macrocyclic complexes of the type [MLX]X2; where L is (C30H28N4), a macrocyclic ligand, M = Cr(III) and Fe(III) and X = Cl-, CH3COO- or NO3-, have been synthesized by template condensation reaction of 1,8-diaminonaphthalene and acetylacetone in the presence of trivalent metal salts in a methanolic medium. The complexes have been formulated as [MLX]X2 due to 1:2 electrolytic nature of these complexes. The complexes have been characterized with the help of elemental analyses, molar conductance measurements, magnetic susceptibility measurements, electronic, infrared, far infrared, Mass spectral studies and molecular modelling. Molecular weight of these complexes indicates their monomeric nature. On the basis of all these studies, a five coordinated square pyramidal geometry has been proposed for all these complexes. These metal complexes have also been screened for their in vitro antimicrobial activities.

PyramidalExplorer: A New Interactive Tool to Explore Morpho-Functional Relations of Human Pyramidal Neurons.

PubMed

Toharia, Pablo; Robles, Oscar D; Fernaud-Espinosa, Isabel; Makarova, Julia; Galindo, Sergio E; Rodriguez, Angel; Pastor, Luis; Herreras, Oscar; DeFelipe, Javier; Benavides-Piccione, Ruth

2015-01-01

This work presents PyramidalExplorer, a new tool to interactively explore and reveal the detailed organization of the microanatomy of pyramidal neurons with functionally related models. It consists of a set of functionalities that allow possible regional differences in the pyramidal cell architecture to be interactively discovered by combining quantitative morphological information about the structure of the cell with implemented functional models. The key contribution of this tool is the morpho-functional oriented design that allows the user to navigate within the 3D dataset, filter and perform Content-Based Retrieval operations. As a case study, we present a human pyramidal neuron with over 9000 dendritic spines in its apical and basal dendritic trees. Using PyramidalExplorer, we were able to find unexpected differential morphological attributes of dendritic spines in particular compartments of the neuron, revealing new aspects of the morpho-functional organization of the pyramidal neuron.

PyramidalExplorer: A New Interactive Tool to Explore Morpho-Functional Relations of Human Pyramidal Neurons

PubMed Central

Toharia, Pablo; Robles, Oscar D.; Fernaud-Espinosa, Isabel; Makarova, Julia; Galindo, Sergio E.; Rodriguez, Angel; Pastor, Luis; Herreras, Oscar; DeFelipe, Javier; Benavides-Piccione, Ruth

2016-01-01

This work presents PyramidalExplorer, a new tool to interactively explore and reveal the detailed organization of the microanatomy of pyramidal neurons with functionally related models. It consists of a set of functionalities that allow possible regional differences in the pyramidal cell architecture to be interactively discovered by combining quantitative morphological information about the structure of the cell with implemented functional models. The key contribution of this tool is the morpho-functional oriented design that allows the user to navigate within the 3D dataset, filter and perform Content-Based Retrieval operations. As a case study, we present a human pyramidal neuron with over 9000 dendritic spines in its apical and basal dendritic trees. Using PyramidalExplorer, we were able to find unexpected differential morphological attributes of dendritic spines in particular compartments of the neuron, revealing new aspects of the morpho-functional organization of the pyramidal neuron. PMID:26778972

Impurity-induced disorder in III-nitride materials and devices

DOEpatents

Wierer, Jr., Jonathan J; Allerman, Andrew A

2014-11-25

A method for impurity-induced disordering in III-nitride materials comprises growing a III-nitride heterostructure at a growth temperature and doping the heterostructure layers with a dopant during or after the growth of the heterostructure and post-growth annealing of the heterostructure. The post-growth annealing temperature can be sufficiently high to induce disorder of the heterostructure layer interfaces.

Circuit-specific intracortical hyperconnectivity in mice with deletion of the autism-associated Met receptor tyrosine kinase

PubMed Central

Qiu, Shenfeng; Anderson, Charles T.; Levitt, Pat; Shepherd, Gordon M. G.

2011-01-01

Local hyperconnectivity in the neocortex is a hypothesized pathophysiological state in autism spectrum disorder (ASD). MET, a receptor tyrosine kinase that regulates dendrite and spine morphogenesis, has been established as a risk gene for ASD. Here, we analyzed the synaptic circuit organization of identified pyramidal neurons in the anterior frontal cortex of mice with a dorsal pallium derived, conditional knockout (cKO) of Met. Synaptic mapping by glutamate uncaging identified layer 2/3 as the main source of local excitatory input to layer 5 projection neurons in controls. In both cKO and heterozygotes this pathway was stronger by a factor of ~2. This increase was both sub-layer and projection-class specific, restricted to corticostriatal neurons in upper layer 5B, and not neighboring corticopontine neurons. Paired recordings in cKO slices demonstrated increased unitary connectivity. We propose that excitatory hyperconnectivity in specific neocortical microcircuits constitutes a physiological basis for Met-mediated ASD risk. PMID:21490227

Experience-Dependent Rewiring of Specific Inhibitory Connections in Adult Neocortex

PubMed Central

Kätzel, Dennis; Miesenböck, Gero

2014-01-01

Although neocortical connectivity is remarkably stereotyped, the abundance of some wiring motifs varies greatly between cortical areas. To examine if regional wiring differences represent functional adaptations, we have used optogenetic raster stimulation to map the laminar distribution of GABAergic interneurons providing inhibition to pyramidal cells in layer 2/3 (L2/3) of adult mouse barrel cortex during sensory deprivation and recovery. Whisker trimming caused large, motif-specific changes in inhibitory synaptic connectivity: ascending inhibition from deep layers 4 and 5 was attenuated to 20%–45% of baseline, whereas inhibition from superficial layers remained stable (L2/3) or increased moderately (L1). The principal mechanism of deprivation-induced plasticity was motif-specific changes in inhibitory-to-excitatory connection probabilities; the strengths of extant connections were left unaltered. Whisker regrowth restored the original balance of inhibition from deep and superficial layers. Targeted, reversible modifications of specific inhibitory wiring motifs thus contribute to the adaptive remodeling of cortical circuits. PMID:24586113

Virtual Reality Tumor Resection: The Force Pyramid Approach.

PubMed

Sawaya, Robin; Bugdadi, Abdulgadir; Azarnoush, Hamed; Winkler-Schwartz, Alexander; Alotaibi, Fahad E; Bajunaid, Khalid; AlZhrani, Gmaan A; Alsideiri, Ghusn; Sabbagh, Abdulrahman J; Del Maestro, Rolando F

2018-06-01

The force pyramid is a novel visual representation allowing spatial delineation of instrument force application during surgical procedures. In this study, the force pyramid concept is employed to create and quantify dominant hand, nondominant hand, and bimanual force pyramids during resection of virtual reality brain tumors. To address 4 questions: Do ergonomics and handedness influence force pyramid structure? What are the differences between dominant and nondominant force pyramids? What is the spatial distribution of forces applied in specific tumor quadrants? What differentiates "expert" and "novice" groups regarding their force pyramids? Using a simulated aspirator in the dominant hand and a simulated sucker in the nondominant hand, 6 neurosurgeons and 14 residents resected 8 different tumors using the CAE NeuroVR virtual reality neurosurgical simulation platform (CAE Healthcare, Montréal, Québec and the National Research Council Canada, Boucherville, Québec). Position and force data were used to create force pyramids and quantify tumor quadrant force distribution. Force distribution quantification demonstrates the critical role that handedness and ergonomics play on psychomotor performance during simulated brain tumor resections. Neurosurgeons concentrate their dominant hand forces in a defined crescent in the lower right tumor quadrant. Nondominant force pyramids showed a central peak force application in all groups. Bimanual force pyramids outlined the combined impact of each hand. Distinct force pyramid patterns were seen when tumor stiffness, border complexity, and color were altered. Force pyramids allow delineation of specific tumor regions requiring greater psychomotor ability to resect. This information can focus and improve resident technical skills training.

A Corticocortical Circuit Directly Links Retrosplenial Cortex to M2 in the Mouse

PubMed Central

Radulovic, Jelena

2016-01-01

Retrosplenial cortex (RSC) is a dorsomedial parietal area involved in a range of cognitive functions, including episodic memory, navigation, and spatial memory. Anatomically, the RSC receives inputs from dorsal hippocampal networks and in turn projects to medial neocortical areas. A particularly prominent projection extends rostrally to the posterior secondary motor cortex (M2), suggesting a functional corticocortical link from the RSC to M2 and thus a bridge between hippocampal and neocortical networks involved in mnemonic and sensorimotor aspects of navigation. We investigated the cellular connectivity in this RSC→M2 projection in the mouse using optogenetic photostimulation, retrograde labeling, and electrophysiology. Axons from RSC formed monosynaptic excitatory connections onto M2 pyramidal neurons across layers and projection classes, including corticocortical/intratelencephalic neurons (reciprocally and callosally projecting) in layers 2–6, pyramidal tract neurons (corticocollicular, corticopontine) in layer 5B, and, to a lesser extent, corticothalamic neurons in layer 6. In addition to these direct connections, disynaptic connections were made via posterior parietal cortex (RSC→PPC→M2) and anteromedial thalamus (RSC→AM→M2). In the reverse direction, axons from M2 monosynaptically excited M2-projecting corticocortical neurons in the RSC, especially in the superficial layers of the dysgranular region. These findings establish an excitatory RSC→M2 corticocortical circuit that engages diverse types of excitatory projection neurons in the downstream area, suggesting a basis for direct communication from dorsal hippocampal networks involved in spatial memory and navigation to neocortical networks involved in diverse aspects of sensorimotor integration and motor control. SIGNIFICANCE STATEMENT Corticocortical pathways interconnect cortical areas extensively, but the cellular connectivity in these pathways remains largely uncharacterized. Here, we show that a posterior part of secondary motor cortex receives corticocortical axons from the rostral retrosplenial cortex (RSC) and these form monosynaptic excitatory connections onto a wide spectrum of excitatory projection neurons in this area. Our results define a cellular basis for direct communication from RSC to this medial frontal area, suggesting a direct link from dorsal hippocampal networks involved in spatial cognition and navigation (the “map”) to sensorimotor networks involved the control of movement (the “motor”). PMID:27605612

Striate cortical contribution to the transcorneal electrically evoked response of the visual system.

PubMed

Shimazu, K; Miyake, Y; Fukatsu, Y; Watanabe, S

1996-01-01

Analyses of current-source-density (CSD) and multiple unit activity (MUA) in area 17 of the cat were performed to determine the sources of the cortical transcorneal electrically evoked response. Cortical field potential, CSD and MUA profiles were obtained with multi-electrodes. CSD findings include: current sinks (inward cell membrane current) within 20 ms latency, in layers 4 and 6 of the striate cortex; current sinks corresponding to N3 (negative component of the EER; latency, 35 ms) in layer 4 and lower layer 3 with current sources (outward cell membrane current) for N3 in the supragranular layers; current sinks with latency over 40 ms in the supragranular layers. In the layers 4 and 6, simultaneous MUA was seen. When the stimulus frequency was increased or with dual stimulation, the N3 current sinks were decreased. This indicates that N1 (latency, 9 ms) and N2 (latency, 20 ms) reflect near-field potentials in layers 4 and 6, generated by geniculocortical afferents, and that N3 is a post- and polysynaptic component. It is also suggested that dipoles composed of cell bodies and the apical dendrites of pyramidal cells of layer 3, generated by satellite cells in layer 4, play a major role in generating N3.

Comparative analysis of cortical layering and supragranular layer enlargement in rodent carnivore and primate species.

PubMed

Hutsler, Jeffrey J; Lee, Dong-Geun; Porter, Kristin K

2005-08-02

The mammalian cerebral cortex is composed of individual layers characterized by the cell types they contain and their afferent and efferent connections. The current study examined the raw, and size-normalized, laminar thicknesses in three cortical regions (somatosensory, motor, and premotor) of fourteen species from three orders of mammals: primates, carnivores, and rodents. The proportional size of the pyramidal cell layers (supra- and infragranular) varied between orders but was similar within orders despite wide variance in absolute cortical thickness. Further, supragranular layer thickness was largest in primates (46 +/- 3 percent), followed by carnivores (36 +/- 3 percent), and then rodents (19 +/- 4 percent), suggesting a distinct difference in the proportion of cortex devoted to corticocortical connectivity across these orders. Although measures of supragranular layer thickness are highly correlated with measures of overall brain size, such associations are not present when independent contrasts are used to control for phylogenetic inertia. Interestingly, neurogenesis time span remains strongly associated with supragranular layer thickness despite size normalization and controlling for phylogenetic inertia. Such layering differences between orders, and similarities amongst species within an order, suggest that supragranular layer expansion may have occurred early in mammalian evolution and may be related to ontogenetic variables such as neurogenesis time span rather than measures of overall size.

Self-organization processes and topological defects in nanolayers in a nematic liquid crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chuvyrov, A. N.; Girfanova, F. M.; Mal'tsev, I. S.

Atomic force microscopy is used to study the self-organization processes that occur during the formation of topological defects in nanomolecular layers in a nematic liquid crystal with the homeotropic orientation of its molecules with respect to the substrate. In this case, a smectic monolayer with a thickness of one molecule length (about 2.2 nm) forms on the substrate, and a nanomolecular layer of a nematic liquid crystal forms above this monolayer. In such virtually two-dimensional layers, numerous different nanoclusters, namely, hut structures, pyramids, raft structures with symmetry C{sub nm} (where n = 2, 4, 5, 6, 7, ?, {infinity}), cones,more » and nanopools, form [1]. They have a regular shape close to the geometry of solid crystals. Modulated linear structures and topological point defects appear spontaneously in the nanopools and raft structures.« less

The relativistic titls of Giza pyramids' entrance-passages

NASA Astrophysics Data System (ADS)

Aboulfotouh, H.

The tilts of Giza pyramids' entrance-passages have never been considered as if they were the result of relativistic mathematical equations, and never been thought to encode the Earth's obliquity parameters. This paper presents an attempt to retrieve the method of establishing the equations that the pyramids' designer used to quantify the entrance-passages' tilts of these architectonic masterpieces. It proves that the pyramids' designer was able to include the geographic, astronomical and time parameters in one relativistic equation, encoding the date of the design of the Giza pyramids in the tilt of the entrance passage of the great pyramid.

Sublingual pyramidal lobe. Complications of subtotal thyroidectomy for Graves' disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sternberg, J.L.

1986-11-01

A potential complication of subtotal thyroidectomy where a large pyramidal lobe is present is described. The pyramidal lobe normally is immobilized inferiorly by its attachment to the thyroidal isthmus. When the isthmus is removed and the pyramidal lobe is left in situ during subtotal thyroidectomy its superior attachments will allow the pyramidal lobe to become situated sublingually. This may produce gagging and nausea. To avoid the complication, it is recommended that the pyramidal lobe be removed during subtotal thyroidectomy. If the patient also is thyrotoxic, I-131 can be used to treat this complication successfully.

The perforant path projection to hippocampal area CA1 in the rat hippocampal-entorhinal cortex combined slice.

PubMed

Empson, R M; Heinemann, U

1995-05-01

1. The perforant path projection from layer III of the entorhinal cortex to CA1 of the hippocampus was studied within a hippocampal-entorhinal combined slice preparation. We prevented contamination from the other main hippocampal pathways by removal of CA3 and the dentate gyrus. 2. Initially the projection was mapped using field potential recordings that suggested an excitatory sink in stratum lacunosum moleculare with an associated source in stratum pyramidale. 3. However, recording intracellularly from CA1 cells, stimulation of the perforant path produced prominent fast GABAA and slow GABAB IPSPs often preceded by small EPSPs. In a small number of cells we observed EPSPs only. 4. CNQX blocked excitatory and inhibitory responses. This indicated the presence of an intervening excitatory synapse between the inhibitory interneurone and the pyramidal cell. 5. Focal bicuculline applications revealed that the major site of GABAA inhibitory input was to stratum radiatum of CA1. 6. The inhibition activated by the perforant path was very effective at reducing simultaneously activated Schaffer collateral mediated EPSPs and suprathreshold-stimulated action potentials. 7. Blockade of fast inhibition increased excitability and enhanced slow inhibition. Both increases relied upon the activation of NMDA receptors. 8. Perforant path inputs activated prominent and effective disynaptic inhibition of CA1 cells. This has significance for the output of hippocampal processing during normal behaviour and also under pathological conditions.

Neurochemical and neuroanatomic effects of 3,4-methylenedioxymethamphetamine (MDMA) in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Virus, R.; Commins, D.; Vosmer, G.

1986-03-05

Rats injected s.c. twice daily for 4 consecutive days with 10,20, or 40 mg/kg MDMA or saline and sacrificed 2 weeks after the last injection showed dose-dependent reductions in serotonin (5-HT) concentrations in hypothalamus, hippocampus (HIP), striatum (STR), somatosensory cortex (SC) and other cortical areas (CTX). 5-HT depletion was maximal in HIP (11.5 +/- 1.7%) and SC (15.3 +/- 3.2%, p<0.001 in both cases) at the 40 mg/kg MDMA dose. Forty mg/kg MDMA also reduced the amounts of dopamine (DA) in STR (78.2 +/- 6.4%, p<0.001) and of norepinephrine (NE) in HIP (74.5 +/- 6.4%, P<0.025) and CTX (77.9 +/-more » 6.1%, p<0.05). In addition, 20 mg/kg MDMA markedly reduced the number of (/sup 3/H)5-HT uptake sites (V/sub max/ 35.2% of control) without affecting the affinity (K/sub m/) in HIP. Fink-Heimer staining showed that rats injected s.c. twice daily for 2 days with 80 mg/kg MDMA had greater degeneration of nerve terminals in STR (p<0.005) and pyramidal cells in Layer III of SC (p<0.01) than did control rats. These results clearly suggest that repeated exposure to MDMA selectively damages serotonergic neurons in the central nervous system of rats.« less

Layer specific and general requirements for ERK/MAPK signaling in the developing neocortex

PubMed Central

Xing, Lei; Larsen, Rylan S; Bjorklund, George Reed; Li, Xiaoyan; Wu, Yaohong; Philpot, Benjamin D; Snider, William D; Newbern, Jason M

2016-01-01

Aberrant signaling through the Raf/MEK/ERK (ERK/MAPK) pathway causes pathology in a family of neurodevelopmental disorders known as 'RASopathies' and is implicated in autism pathogenesis. Here, we have determined the functions of ERK/MAPK signaling in developing neocortical excitatory neurons. Our data reveal a critical requirement for ERK/MAPK signaling in the morphological development and survival of large Ctip2+ neurons in layer 5. Loss of Map2k1/2 (Mek1/2) led to deficits in corticospinal tract formation and subsequent corticospinal neuron apoptosis. ERK/MAPK hyperactivation also led to reduced corticospinal axon elongation, but was associated with enhanced arborization. ERK/MAPK signaling was dispensable for axonal outgrowth of layer 2/3 callosal neurons. However, Map2k1/2 deletion led to reduced expression of Arc and enhanced intrinsic excitability in both layers 2/3 and 5, in addition to imbalanced synaptic excitation and inhibition. These data demonstrate selective requirements for ERK/MAPK signaling in layer 5 circuit development and general effects on cortical pyramidal neuron excitability. DOI: http://dx.doi.org/10.7554/eLife.11123.001 PMID:26848828

Feedback Inhibition Shapes Emergent Computational Properties of Cortical Microcircuit Motifs.

PubMed

Jonke, Zeno; Legenstein, Robert; Habenschuss, Stefan; Maass, Wolfgang

2017-08-30

Cortical microcircuits are very complex networks, but they are composed of a relatively small number of stereotypical motifs. Hence, one strategy for throwing light on the computational function of cortical microcircuits is to analyze emergent computational properties of these stereotypical microcircuit motifs. We are addressing here the question how spike timing-dependent plasticity shapes the computational properties of one motif that has frequently been studied experimentally: interconnected populations of pyramidal cells and parvalbumin-positive inhibitory cells in layer 2/3. Experimental studies suggest that these inhibitory neurons exert some form of divisive inhibition on the pyramidal cells. We show that this data-based form of feedback inhibition, which is softer than that of winner-take-all models that are commonly considered in theoretical analyses, contributes to the emergence of an important computational function through spike timing-dependent plasticity: The capability to disentangle superimposed firing patterns in upstream networks, and to represent their information content through a sparse assembly code. SIGNIFICANCE STATEMENT We analyze emergent computational properties of a ubiquitous cortical microcircuit motif: populations of pyramidal cells that are densely interconnected with inhibitory neurons. Simulations of this model predict that sparse assembly codes emerge in this microcircuit motif under spike timing-dependent plasticity. Furthermore, we show that different assemblies will represent different hidden sources of upstream firing activity. Hence, we propose that spike timing-dependent plasticity enables this microcircuit motif to perform a fundamental computational operation on neural activity patterns. Copyright © 2017 the authors 0270-6474/17/378511-13$15.00/0.

Midazolam inhibits hippocampal long-term potentiation and learning through dual central and peripheral benzodiazepine receptor activation and neurosteroidogenesis.

PubMed

Tokuda, Kazuhiro; O'Dell, Kazuko A; Izumi, Yukitoshi; Zorumski, Charles F

2010-12-15

Benzodiazepines (BDZs) enhance GABA(A) receptor inhibition by direct actions on central BDZ receptors (CBRs). Although some BDZs also bind mitochondrial receptors [translocator protein (18 kDa) (TSPO)] and promote the synthesis of GABA-enhancing neurosteroids, the role of neurosteroids in the clinical effects of BDZs is unknown. In rat hippocampal slices, we compared midazolam, an anesthetic BDZ, with clonazepam, an anticonvulsant/anxiolytic BDZ that activates CBRs selectively. Midazolam, but not clonazepam, increased neurosteroid levels in CA1 pyramidal neurons without changing TSPO immunostaining. Midazolam, but not clonazepam, also augmented a form of spike inhibition after stimulation adjacent to the pyramidal cell layer and inhibited induction of long-term potentiation. These effects were prevented by finasteride, an inhibitor of neurosteroid synthesis, or 17PA [17-phenyl-(3α,5α)-androst-16-en-3-ol], a blocker of neurosteroid effects on GABA(A) receptors. Moreover, the synaptic effects were mimicked by a combination of clonazepam with FGIN (2-[2-(4-fluorophenyl)-1H-indol-3-yl]-N,N-dihexylacetamide), a selective TSPO agonist, or a combination of clonazepam with exogenous allopregnanolone. Consistent with these in vitro results, finasteride abolished the effects of midazolam on contextual fear learning when administrated 1 d before midazolam injection. Thus, dual activation of CBRs and TSPO appears to result in unique actions of clinically important BDZs. Furthermore, endogenous neurosteroids are shown to be important regulators of pyramidal neuron function and synaptic plasticity.

Midazolam inhibits hippocampal long-term potentiation and learning through dual central and peripheral benzodiazepine receptor activation and neurosteroidogenesis

PubMed Central

Tokuda, Kazuhiro; O’Dell, Kazuko A.; Izumi, Yukitoshi; Zorumski, Charles F.

2010-01-01

Benzodiazepines (BDZs) enhance γ-aminobutyric acid-A (GABAA) receptor inhibition by direct actions on central BDZ receptors (CBRs). Although some BDZs also bind mitochondrial receptors (translocator protein 18kDa, TSPO) and promote the synthesis of GABA-enhancing neurosteroids, the role of neurosteroids in the clinical effects of BDZs is unknown. In rat hippocampal slices, we compared midazolam, an anesthetic BDZ with clonazepam, an anticonvulsant/anxiolytic BDZ that activates CBRs selectively. Midazolam, but not clonazepam, increased neurosteroid levels in CA1 pyramidal neurons without changing TSPO immunostaining. Midazolam, but not clonazepam, also augmented a form of spike inhibition following stimulation adjacent to the pyramidal cell layer and inhibited induction of long-term potentiation. These effects were prevented by finasteride, an inhibitor of neurosteroid synthesis, or 17PA (17-phenyl-(3α, 5α)-androst-16-en-3-ol), a blocker of neurosteroid effects on GABAA receptors. Moreover, the synaptic effects were mimicked by a combination of clonazepam with FGIN, a selective TSPO agonist, or a combination of clonazepam with exogenous allopregnanolone. Consistent with these in vitro results, finasteride abolished the effects of midazolam on contextual fear learning when administrated one day prior to midazolam injection. Thus, dual activation of CBRs and TSPO appears to result in unique actions of clinically-important BDZs. Furthermore, endogenous neurosteroids are shown to be important regulators of pyramidal neuron function and synaptic plasticity. PMID:21159950

Action potentials reliably invade axonal arbors of rat neocortical neurons

PubMed Central

Cox, Charles L.; Denk, Winfried; Tank, David W.; Svoboda, Karel

2000-01-01

Neocortical pyramidal neurons have extensive axonal arborizations that make thousands of synapses. Action potentials can invade these arbors and cause calcium influx that is required for neurotransmitter release and excitation of postsynaptic targets. Thus, the regulation of action potential invasion in axonal branches might shape the spread of excitation in cortical neural networks. To measure the reliability and extent of action potential invasion into axonal arbors, we have used two-photon excitation laser scanning microscopy to directly image action-potential-mediated calcium influx in single varicosities of layer 2/3 pyramidal neurons in acute brain slices. Our data show that single action potentials or bursts of action potentials reliably invade axonal arbors over a range of developmental ages (postnatal 10–24 days) and temperatures (24°C-30°C). Hyperpolarizing current steps preceding action potential initiation, protocols that had previously been observed to produce failures of action potential propagation in cultured preparations, were ineffective in modulating the spread of action potentials in acute slices. Our data show that action potentials reliably invade the axonal arbors of neocortical pyramidal neurons. Failures in synaptic transmission must therefore originate downstream of action potential invasion. We also explored the function of modulators that inhibit presynaptic calcium influx. Consistent with previous studies, we find that adenosine reduces action-potential-mediated calcium influx in presynaptic terminals. This reduction was observed in all terminals tested, suggesting that some modulatory systems are expressed homogeneously in most terminals of the same neuron. PMID:10931955

Historical transition of eco-structure in a tidal flat caused by expansion of sewerage treatment area.

PubMed

Tatsumoto, Hideki; Ishii, Yuichi; Machida, Motoi; Taki, Kazuo

2004-05-11

An artificial tidal flat was prepared for the mitigation tool on coastal environment. However, it is considered that most of the flat was not restored to the sufficient amenities for aquatic living things, migratory birds, etc. because none of the ecological mechanisms were understood or planned for. It is therefore investigated in this paper that historical transition factors in ecosystem structure are selected and traced with the diffusion of a public sewerage system, and with environmental factors such as water quality, sediment condition, and aquatic producers in the Yatsu Tidal Flat. As a result, it can be defined that the tidal flat, just like a lagoon, was formed artificially with reclamation and development of its circumference at the first step of transition; the water quality and sediment condition gradually became brackish water and muddy sediment conditions, interactively. The ecosystem pyramid forming orderly layers according to trophic level appeared as a high-bio-production potential in its tidal flat. In the second step, i.e., in recent years, the characteristics of water quality and sediment conditions evolved into a foreshore tidal flat, namely, conditions in the flat observed were that the progression of water included a high concentration of chloride ion as seawater and sediment conditions became sandy. Because of that, the inflowing fresh water and organic mater from the land area decreased with the improvement of the public sewerage system. The ecosystem pyramid was distorted into a chaos pyramid, with inversion of Ulva spp.

Pharmacological modulation of the voltage-gated neuronal Kv7/KCNQ/M-channel alters the intrinsic excitability and synaptic responses of pyramidal neurons in rat prefrontal cortex slices.

PubMed

Peng, Hui; Bian, Xi-Ling; Ma, Fu-Cui; Wang, Ke-Wei

2017-09-01

The prefrontal cortex (PFC) critical for higher cognition is implicated in neuropsychiatric diseases, such as Alzheimer's disease, depression and schizophrenia. The voltage-activated Kv7/KCNQ/M-channel or M-current modulates the neuronal excitability that defines the fundamental mechanism of brain function. However, whether M-current functions to regulate the excitability of PFC neurons remains elusive. In this study, we recorded the native M-current from PFC layer V pyramidal neurons in rat brain slices and showed that it modulated the intrinsic excitability and synaptic responses of PFC pyramidal neurons. Application of a specific M-channel blocker XE991 (40 μmol/L) or opener retigabine (10 μmol/L) resulted in inhibition or activation of M-current, respectively. In the current-clamp recordings, inhibition of M-current was evidenced by the increased average spike frequency and the reduced first inter-spike interval (ISI), spike onset latency and fast afterhyperpolarization (fAHP), whereas activation of M-current caused opposite responses. Furthermore, inhibition of M-current significantly increased the amplitude of excitatory postsynaptic potentials (EPSPs) and depolarized the resting membrane potential (RMP) without affecting the miniature EPSC (mEPSC) frequency. These data demonstrate that voltage-gated neuronal Kv7/KCNQ/M-current modulates the excitability and synaptic transmission of PFC neurons, suggesting that pharmacological modulation of M-current in the PFC may exert beneficial effects on cognitive deficits implicated in the pathophysiology of neuropsychiatric disorders.

Evaluation of Trap Designs and Deployment Strategies for Capturing Halyomorpha halys (Hemiptera: Pentatomidae)

PubMed Central

Morrison, William R.; Cullum, John P.; Leskey, Tracy C.

2015-01-01

Halyomorpha halys (Stål) is an invasive pest that attacks numerous crops. For growers to make informed management decisions against H. halys, an effective monitoring tool must be in place. We evaluated various trap designs baited with the two-component aggregation pheromone of H. halys and synergist and deployed in commercial apple orchards. We compared our current experimental standard trap, a black plywood pyramid trap 1.22 m in height deployed between border row apple trees with other trap designs for two growing seasons. These included a black lightweight coroplast pyramid trap of similar dimension, a smaller (29 cm) pyramid trap also ground deployed, a smaller limb-attached pyramid trap, a smaller pyramid trap hanging from a horizontal branch, and a semipyramid design known as the Rescue trap. We found that the coroplast pyramid was the most sensitive, capturing more adults than all other trap designs including our experimental standard. Smaller pyramid traps performed equally in adult captures to our experimental standard, though nymphal captures were statistically lower for the hanging traps. Experimental standard plywood and coroplast pyramid trap correlations were strong, suggesting that standard plywood pyramid traps could be replaced with lighter, cheaper coroplast pyramid traps. Strong correlations with small ground- and limb-deployed pyramid traps also suggest that these designs offer promise as well. Growers may be able to adopt alternative trap designs that are cheaper, lighter, and easier to deploy to monitor H. halys in orchards without a significant loss in sensitivity. PMID:26470309

Structural changes of oviduct of freshwater shrimp, Macrobrachium nipponense (Decapoda, Palaemonidae), during spawning*

PubMed Central

Lu, Jian-ping; Zhang, Xiao-hui; Yu, Xiao-yun

2006-01-01

The structural change of the oviduct of freshwater shrimp (Macrobrachium nipponense) during spawning was examined by electron microscopy. The oviduct wall structural characteristics seem to be influenced significantly by the spawning process. Before the parturition and ovulation, two types of epithelial cells (types I and II) are found in the epithelium. The free surfaces of type I and type II cells have very dense long microvilli. Under the type I and type II cells, are a relatively thick layer of secreting material and a layer of mostly dead cells. After ovulation, two other types of epithelial cells (types III and IV) are found in the oviduct wall epithelium. The free surface of type III cells only has short microvilli scattered on the surface. The thick layer with secreting material and the dead cell layer disappeared at this stage. In some type III cells, the leaking out of cytoplasm from broken cell membrane led to the death of these type III cells. The transformation of all four types of epithelial cells was in the order: IV→I→II→III. PMID:16365928

Investigation of the Great Pyramid of Giza.

ERIC Educational Resources Information Center

Peace, Nigel; And Others

1997-01-01

Describes an activity in which geometry and trigonometry are studied using pyramids. Identical model pyramids are constructed from card stock, along with pyramids of different proportions and cuboids to use as controls. Also includes an investigation of some apparently non-scientific claims. (DDR)

Trends in heteroepitaxy of III-Vs on silicon for photonic and photovoltaic applications

NASA Astrophysics Data System (ADS)

Lourdudoss, Sebastian; Junesand, Carl; Kataria, Himanshu; Metaferia, Wondwosen; Omanakuttan, Giriprasanth; Sun, Yan-Ting; Wang, Zhechao; Olsson, Fredrik

2017-02-01

We present and compare the existing methods of heteroepitaxy of III-Vs on silicon and their trends. We focus on the epitaxial lateral overgrowth (ELOG) method as a means of achieving good quality III-Vs on silicon. Initially conducted primarily by near-equilibrium epitaxial methods such as liquid phase epitaxy and hydride vapour phase epitaxy, nowadays ELOG is being carried out even by non-equilibrium methods such as metal organic vapour phase epitaxy. In the ELOG method, the intermediate defective seed and the mask layers still exist between the laterally grown purer III-V layer and silicon. In a modified ELOG method called corrugated epitaxial lateral overgrowth (CELOG) method, it is possible to obtain direct interface between the III-V layer and silicon. In this presentation we exemplify some recent results obtained by these techniques. We assess the potentials of these methods along with the other existing methods for realizing truly monolithic photonic integration on silicon and III-V/Si heterojunction solar cells.

Correlative Microscopy Combining Secondary Ion Mass Spectrometry and Electron Microscopy: Comparison of Intensity-Hue-Saturation and Laplacian Pyramid Methods for Image Fusion.

PubMed

Vollnhals, Florian; Audinot, Jean-Nicolas; Wirtz, Tom; Mercier-Bonin, Muriel; Fourquaux, Isabelle; Schroeppel, Birgit; Kraushaar, Udo; Lev-Ram, Varda; Ellisman, Mark H; Eswara, Santhana

2017-10-17

Correlative microscopy combining various imaging modalities offers powerful insights into obtaining a comprehensive understanding of physical, chemical, and biological phenomena. In this article, we investigate two approaches for image fusion in the context of combining the inherently lower-resolution chemical images obtained using secondary ion mass spectrometry (SIMS) with the high-resolution ultrastructural images obtained using electron microscopy (EM). We evaluate the image fusion methods with three different case studies selected to broadly represent the typical samples in life science research: (i) histology (unlabeled tissue), (ii) nanotoxicology, and (iii) metabolism (isotopically labeled tissue). We show that the intensity-hue-saturation fusion method often applied for EM-sharpening can result in serious image artifacts, especially in cases where different contrast mechanisms interplay. Here, we introduce and demonstrate Laplacian pyramid fusion as a powerful and more robust alternative method for image fusion. Both physical and technical aspects of correlative image overlay and image fusion specific to SIMS-based correlative microscopy are discussed in detail alongside the advantages, limitations, and the potential artifacts. Quantitative metrics to evaluate the results of image fusion are also discussed.

Morphological evolution and characterization of GaN pyramid arrays fabricated by photo-assisted chemical etching

NASA Astrophysics Data System (ADS)

Zhang, Shiying; Xiu, Xiangqian; Xu, Qingjun; Li, Yuewen; Hua, Xuemei; Chen, Peng; Xie, Zili; Liu, Bin; Zhou, Yugang; Han, Ping; Zhang, Rong; Zheng, Youdou

2016-12-01

GaN pyramid arrays have been successfully synthesized by selective photo-assisted chemical etching in a K2S2O8/KOH solution. A detailed analysis of time evolution of surface morphology has been conducted, which describes an etching process of GaN pyramids. Room temperature cathodoluminescence images indicate that these pyramids are composed of crystalline GaN surrounding dislocations, which is caused by the greater recombination rate of electrons and holes at dislocation than that of crystalline GaN. The Raman results show a stress relaxation in GaN pyramids compared with unetched GaN. The optical property of both unetched GaN and GaN pyramids has been studied by photoluminescence. The formation mechanism and feature of GaN pyramids are also rationally explained.

Modification of dendritic development.

PubMed

Feria-Velasco, Alfredo; del Angel, Alma Rosa; Gonzalez-Burgos, Ignacio

2002-01-01

Since 1890 Ramón y Cajal strongly defended the theory that dendrites and their processes and spines had a function of not just nutrient transport to the cell body, but they had an important conductive role in neural impulse transmission. He extensively discussed and supported this theory in the Volume 1 of his extraordinary book Textura del Sistema Nervioso del Hombre y de los Vertebrados. Also, Don Santiago significantly contributed to a detailed description of the various neural components of the hippocampus and cerebral cortex during development. Extensive investigation has been done in the last Century related to the functional role of these complex brain regions, and their association with learning, memory and some limbic functions. Likewise, the organization and expression of neuropsychological qualities such as memory, exploratory behavior and spatial orientation, among others, depend on the integrity and adequate functional activity of the cerebral cortex and hippocampus. It is known that brain serotonin synthesis and release depend directly and proportionally on the availability of its precursor, tryptophan (TRY). By using a chronic TRY restriction model in rats, we studied their place learning ability in correlation with the dendritic spine density of pyramidal neurons in field CA1 of the hippocampus during postnatal development. We have also reported alterations in the maturation pattern of the ability for spontaneous alternation and task performance evaluating short-term memory, as well as adverse effects on the density of dendritic spines of hippocampal CA1 field pyramidal neurons and on the dendritic arborization and the number of dendritic spines of pyramidal neurons from the third layer of the prefrontal cortex using the same model of TRY restriction. The findings obtained in these studies employing a modified Golgi method, can be interpreted as a trans-synaptic plastic response due to understimulation of serotoninergic receptors located in the hippocampal Ammon's horn and, particularly, on the CA1 field pyramidal neurons, as well as on afferences to the hippocampus which needs to be further investigated.

Expression of Kv3.1b potassium channel is widespread in macaque motor cortex pyramidal cells: A histological comparison between rat and macaque

PubMed Central

Soares, David; Goldrick, Isabelle; Lemon, Roger N.; Kraskov, Alexander; Greensmith, Linda

2017-01-01

Abstract There are substantial differences across species in the organization and function of the motor pathways. These differences extend to basic electrophysiological properties. Thus, in rat motor cortex, pyramidal cells have long duration action potentials, while in the macaque, some pyramidal neurons exhibit short duration “thin” spikes. These differences may be related to the expression of the fast potassium channel Kv3.1b, which in rat interneurons is associated with generation of thin spikes. Rat pyramidal cells typically lack these channels, while there are reports that they are present in macaque pyramids. Here we made a systematic, quantitative comparison of the Kv3.1b expression in sections from macaque and rat motor cortex, using two different antibodies (NeuroMab, Millipore). As our standard reference, we examined, in the same sections, Kv3.1b staining in parvalbumin‐positive interneurons, which show strong Kv3.1b immunoreactivity. In macaque motor cortex, a large sample of pyramidal neurons were nearly all found to express Kv3.1b in their soma membranes. These labeled neurons were identified as pyramidal based either by expression of SMI32 (a pyramidal marker), or by their shape and size, and lack of expression of parvalbumin (a marker for some classes of interneuron). Large (Betz cells), medium, and small pyramidal neurons all expressed Kv3.1b. In rat motor cortex, SMI32‐postive pyramidal neurons expressing Kv3.1b were very rare and weakly stained. Thus, there is a marked species difference in the immunoreactivity of Kv3.1b in pyramidal neurons, and this may be one of the factors explaining the pronounced electrophysiological differences between rat and macaque pyramidal neurons. PMID:28213922

Evaluation of the Cost-Effectiveness of Pyramidal, Modified Pyramidal and Monoscreen Traps for the Control of the Tsetse Fly, Glossina fuscipes fuscipes, in Uganda

PubMed Central

Abila, P.P.; Okello-Onen, J.; Okoth, J.O.; Matete, G.O.; Wamwiri, F.; Politzar, H.

2007-01-01

Several trap designs have been used for sampling and control of the tsetse fly, Glossina fuscipes fuscipes, Newstead (Diptera: Glossinidae) based on preferences of individual researchers and program managers with little understanding of the comparative efficiency and cost-effectiveness of trap designs. This study was carried out to evaluate the cost-effectiveness of four commonly used trap designs: monoscreen, modified pyramidal and pyramidal, relative to the standard biconical trap. The study was performed under high tsetse challenge on Buvuma Island, Lake Victoria, Uganda, using a 4 × 4 Latin square design replicated 3 times, so as to separate the trap positions and day effects from the treatment effect. A total of 12 trap positions were tested over 4 days. The monoscreen trap caught significantly higher numbers of G. f. fuscipes (P<0.05) followed by biconical, modified pyramidal and pyramidal traps. Analysis of variance showed that treatment factor was a highly significant source of variation in the data. The index of increase in trap catches relative biconical were O.60 (pyramidal), 0.68 (modified pyramidal) and 1.25 (monoscreen). The monoscreen trap was cheaper (US$ 2.61) and required less material to construct than pyramidal trap (US$ 3.48), biconical and the modified pyramidal traps (US$ 4.06 each). Based on the number of flies caught per meter of material, the monoscreen trap proved to be the most cost-effective (232 flies/m) followed by the biconical trap (185 flies/m). The modified pyramidal and the pyramidal traps caught 112 and 125 flies/m, respectively. PMID:20345292

Yellow to greenish-blue colour-tunable photoluminescence and 4f-centered slow magnetic relaxation in a cyanido-bridged Dy(III)(4-hydroxypyridine)-Co(III) layered material.

PubMed

Chorazy, Szymon; Wang, Junhao; Ohkoshi, Shin-Ichi

2016-09-14

A cyanido-bridged layered {[Dy(III)(4-OHpy)2(H2O)3][Co(III)(CN)6]}·0.5H2O (1) (4-OHpy = 4-hydroxypyridine) framework with dual photo-luminescence and magnetic properties was prepared. 1 exhibits visible emission whose color, yellow to greenish-blue, is switchable by selected wavelengths of UV excitation light. Magnetic data revealed that 1 shows not only the slow magnetic relaxation of a typical Dy(III) single-ion origin but also the relaxation process caused by the magnetic dipole-magnetic dipole interactions between the neighbouring Dy(III) centers.

RBS characterization of arsenic(III) partitioning from aqueous phase into the active layers of thin-film composite NF/RO membranes.

PubMed

Mi, Baoxia; Mariñas, Benito J; Cahill, David G

2007-05-01

The main objective of this study was to apply Rutherford backscattering spectrometry (RBS) for characterizing the partitioning of arsenic(III) from aqueous phase into the active layer of NF/RO membranes. NF/RO membranes with active layer materials including polyamide (PA), PA-polyvinyl alcohol derivative (PVA), and sulfonated-polyethersulfone (SPES) were investigated. The partition coefficient was found to be constant in the investigated As-(III) concentration range of 0.005-0.02 M at each pH investigated. The partitioning of As(III) when predominantly present as H3AsO3 (pH 3.5-8.0) was not affected by pH. In contrast, the partition coefficient of As(III) at pH 10.5, when it was predominantly present as H2AsO3-, was found to be approximately 33-49% lower than that of H3AsO3. The partition coefficients of H3AsO3 and H2AsO3- for membranes containing PA in their active layers were within the respective ranges of 6.2-8.1 and 3.6-5.4, while the corresponding values (4.8 and 3.0, respectively) for the membrane with SPES active layer were approximately 30% lower than the average values for the PA membranes.

Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jeomoh, E-mail: jkim610@gatech.edu; Ji, Mi-Hee; Detchprohm, Theeradetch

2015-09-28

Unintentional incorporation of gallium (Ga) in InAlN layers grown with different molar flow rates of Group-III precursors by metalorganic chemical vapor deposition has been experimentally investigated. The Ga mole fraction in the InAl(Ga)N layer was increased significantly with the trimethylindium (TMIn) flow rate, while the trimethylaluminum flow rate controls the Al mole fraction. The evaporation of metallic Ga from the liquid phase eutectic system between the pyrolized In from injected TMIn and pre-deposited metallic Ga was responsible for the Ga auto-incorporation into the InAl(Ga)N layer. The theoretical calculation on the equilibrium vapor pressure of liquid phase Ga and the effectivemore » partial pressure of Group-III precursors based on growth parameters used in this study confirms the influence of Group-III precursors on Ga auto-incorporation. More Ga atoms can be evaporated from the liquid phase Ga on the surrounding surfaces in the growth chamber and then significant Ga auto-incorporation can occur due to the high equilibrium vapor pressure of Ga comparable to effective partial pressure of input Group-III precursors during the growth of InAl(Ga)N layer.« less

Theoretical study of pyramid sizes and scattering effects in silicon photovoltaic module stacks.

PubMed

Höhn, Oliver; Tucher, Nico; Bläsi, Benedikt

2018-03-19

Front side pyramids are the industrial standard for wafer based monocrystalline silicon solar cells. These pyramids fulfill two tasks: They act as anti-reflective structure on the one hand and as a light-trapping structure on the other hand. In recent development smaller pyramids with sizes below 1 µm attract more and more interest. In this paper an optical analysis of periodically arranged front side pyramids is performed. The impact on the reflectance as well as on the useful absorption within the solar cell is investigated depending on the pyramids size, the amount of additional scattering in the system and the quality of the rear side reflector. In contrast to other investigations not only the solar cell, but the full photovoltaic (PV) module stack is considered. This can strongly influence results, as we show in this paper. The results indicate that in a PV module stack with realistic assumptions for the amount of scattering as well as for the rear side reflectance only small differences for pyramids with sizes above 600 nm occur. Preliminary conclusions for random pyramids deduced from these results for periodically arranged pyramids indicate that these differences could become even smaller.

Parvalbumin interneurons and calretinin fibers arising from the thalamic nucleus reuniens degenerate in the subiculum after kainic acid-induced seizures

PubMed Central

Drexel, M.; Preidt, A.P.; Kirchmair, E.; Sperk, G.

2011-01-01

The subiculum is the major output area of the hippocampus. It is closely interconnected with the entorhinal cortex and other parahippocampal areas. In animal models of temporal lobe epilepsy (TLE) and in TLE patients it exerts increased network excitability and may crucially contribute to the propagation of limbic seizures. Using immunohistochemistry and in situ-hybridization we now investigated neuropathological changes affecting parvalbumin and calretinin containing neurons in the subiculum and other parahippocampal areas after kainic acid-induced status epilepticus. We observed prominent losses in parvalbumin containing interneurons in the subiculum and entorhinal cortex, and in the principal cell layers of the pre- and parasubiculum. Degeneration of parvalbumin-positive neurons was associated with significant precipitation of parvalbumin-immunoreactive debris 24 h after kainic acid injection. In the subiculum the superficial portion of the pyramidal cell layer was more severely affected than its deep part. In the entorhinal cortex, the deep layers were more severely affected than the superficial ones. The decrease in number of parvalbumin-positive neurons in the subiculum and entorhinal cortex correlated with the number of spontaneous seizures subsequently experienced by the rats. The loss of parvalbumin neurons thus may contribute to the development of spontaneous seizures. On the other hand, surviving parvalbumin neurons revealed markedly increased expression of parvalbumin mRNA notably in the pyramidal cell layer of the subiculum and in all layers of the entorhinal cortex. This indicates increased activity of these neurons aiming to compensate for the partial loss of this functionally important neuron population. Furthermore, calretinin-positive fibers terminating in the molecular layer of the subiculum, in sector CA1 of the hippocampus proper and in the entorhinal cortex degenerated together with their presumed perikarya in the thalamic nucleus reuniens. In addition, a significant loss of calretinin containing interneurons was observed in the subiculum. Notably, the loss in parvalbumin positive neurons in the subiculum equaled that in human TLE. It may result in marked impairment of feed-forward inhibition of the temporo-ammonic pathway and may significantly contribute to epileptogenesis. Similarly, the loss of calretinin-positive fiber tracts originating from the nucleus reuniens thalami significantly contributes to the rearrangement of neuronal circuitries in the subiculum and entorhinal cortex during epileptogenesis. PMID:21616128

The Formation and Characterization of GaN Hexagonal Pyramids

NASA Astrophysics Data System (ADS)

Zhang, Shi-Ying; Xiu, Xiang-Qian; Lin, Zeng-Qin; Hua, Xue-Mei; Xie, Zi-Li; Zhang, Rong; Zheng, You-Dou

2013-05-01

GaN with hexagonal pyramids is fabricated using the photo-assisted electroless chemical etching method. Defective areas of the GaN substrate are selectively etched in a mixed solution of KOH and K2S2O8 under ultraviolet illumination, producing submicron-sized pyramids. Hexagonal pyramids on the etched GaN with well-defined {101¯1¯} facets and very sharp tips are formed. High-resolution x-ray diffraction shows that etched GaN with pyramids has a higher crystal quality, and micro-Raman spectra reveal a tensile stress relaxation in GaN with pyramids compared with normal GaN. The cathodoluminescence intensity of GaN after etching is significantly increased by three times, which is attributed to the reduction in the internal reflection, high-quality GaN with pyramids and the Bragg effect.

Sensory-evoked LTP driven by dendritic plateau potentials in vivo.

PubMed

Gambino, Frédéric; Pagès, Stéphane; Kehayas, Vassilis; Baptista, Daniela; Tatti, Roberta; Carleton, Alan; Holtmaat, Anthony

2014-11-06

Long-term synaptic potentiation (LTP) is thought to be a key process in cortical synaptic network plasticity and memory formation. Hebbian forms of LTP depend on strong postsynaptic depolarization, which in many models is generated by action potentials that propagate back from the soma into dendrites. However, local dendritic depolarization has been shown to mediate these forms of LTP as well. As pyramidal cells in supragranular layers of the somatosensory cortex spike infrequently, it is unclear which of the two mechanisms prevails for those cells in vivo. Using whole-cell recordings in the mouse somatosensory cortex in vivo, we demonstrate that rhythmic sensory whisker stimulation efficiently induces synaptic LTP in layer 2/3 (L2/3) pyramidal cells in the absence of somatic spikes. The induction of LTP depended on the occurrence of NMDAR (N-methyl-d-aspartate receptor)-mediated long-lasting depolarizations, which bear similarities to dendritic plateau potentials. In addition, we show that whisker stimuli recruit synaptic networks that originate from the posteromedial complex of the thalamus (POm). Photostimulation of channelrhodopsin-2 expressing POm neurons generated NMDAR-mediated plateau potentials, whereas the inhibition of POm activity during rhythmic whisker stimulation suppressed the generation of those potentials and prevented whisker-evoked LTP. Taken together, our data provide evidence for sensory-driven synaptic LTP in vivo, in the absence of somatic spiking. Instead, LTP is mediated by plateau potentials that are generated through the cooperative activity of lemniscal and paralemniscal synaptic circuitry.

Predicting the synaptic information efficacy in cortical layer 5 pyramidal neurons using a minimal integrate-and-fire model.

PubMed

London, Michael; Larkum, Matthew E; Häusser, Michael

2008-11-01

Synaptic information efficacy (SIE) is a statistical measure to quantify the efficacy of a synapse. It measures how much information is gained, on the average, about the output spike train of a postsynaptic neuron if the input spike train is known. It is a particularly appropriate measure for assessing the input-output relationship of neurons receiving dynamic stimuli. Here, we compare the SIE of simulated synaptic inputs measured experimentally in layer 5 cortical pyramidal neurons in vitro with the SIE computed from a minimal model constructed to fit the recorded data. We show that even with a simple model that is far from perfect in predicting the precise timing of the output spikes of the real neuron, the SIE can still be accurately predicted. This arises from the ability of the model to predict output spikes influenced by the input more accurately than those driven by the background current. This indicates that in this context, some spikes may be more important than others. Lastly we demonstrate another aspect where using mutual information could be beneficial in evaluating the quality of a model, by measuring the mutual information between the model's output and the neuron's output. The SIE, thus, could be a useful tool for assessing the quality of models of single neurons in preserving input-output relationship, a property that becomes crucial when we start connecting these reduced models to construct complex realistic neuronal networks.

Enlargement of Axo-Somatic Contacts Formed by GAD-Immunoreactive Axon Terminals onto Layer V Pyramidal Neurons in the Medial Prefrontal Cortex of Adolescent Female Mice Is Associated with Suppression of Food Restriction-Evoked Hyperactivity and Resilience to Activity-Based Anorexia

PubMed Central

Chen, Yi-Wen; Wable, Gauri Satish; Chowdhury, Tara Gunkali; Aoki, Chiye

2016-01-01

Many, but not all, adolescent female mice that are exposed to a running wheel while food restricted (FR) become excessive wheel runners, choosing to run even during the hours of food availability, to the point of death. This phenomenon is called activity-based anorexia (ABA). We used electron microscopic immunocytochemistry to ask whether individual differences in ABA resilience may correlate with the lengths of axo-somatic contacts made by GABAergic axon terminals onto layer 5 pyramidal neurons (L5P) in the prefrontal cortex. Contact lengths were, on average, 40% greater for the ABA-induced mice, relative to controls. Correspondingly, the proportion of L5P perikaryal plasma membrane contacted by GABAergic terminals was 45% greater for the ABA mice. Contact lengths in the anterior cingulate cortex correlated negatively and strongly with the overall wheel activity after FR (R = −0.87, P < 0.01), whereas those in the prelimbic cortex correlated negatively with wheel running specifically during the hours of food availability of the FR days (R = −0.84, P < 0.05). These negative correlations support the idea that increases in the glutamic acid decarboxylase (GAD) terminal contact lengths onto L5P contribute toward ABA resilience through suppression of wheel running, a behavior that is intrinsically rewarding and helpful for foraging but maladaptive within a cage. PMID:25979087

A morphologically preserved multi-resolution TIN surface modeling and visualization method for virtual globes

NASA Astrophysics Data System (ADS)

Zheng, Xianwei; Xiong, Hanjiang; Gong, Jianya; Yue, Linwei

2017-07-01

Virtual globes play an important role in representing three-dimensional models of the Earth. To extend the functioning of a virtual globe beyond that of a "geobrowser", the accuracy of the geospatial data in the processing and representation should be of special concern for the scientific analysis and evaluation. In this study, we propose a method for the processing of large-scale terrain data for virtual globe visualization and analysis. The proposed method aims to construct a morphologically preserved multi-resolution triangulated irregular network (TIN) pyramid for virtual globes to accurately represent the landscape surface and simultaneously satisfy the demands of applications at different scales. By introducing cartographic principles, the TIN model in each layer is controlled with a data quality standard to formulize its level of detail generation. A point-additive algorithm is used to iteratively construct the multi-resolution TIN pyramid. The extracted landscape features are also incorporated to constrain the TIN structure, thus preserving the basic morphological shapes of the terrain surface at different levels. During the iterative construction process, the TIN in each layer is seamlessly partitioned based on a virtual node structure, and tiled with a global quadtree structure. Finally, an adaptive tessellation approach is adopted to eliminate terrain cracks in the real-time out-of-core spherical terrain rendering. The experiments undertaken in this study confirmed that the proposed method performs well in multi-resolution terrain representation, and produces high-quality underlying data that satisfy the demands of scientific analysis and evaluation.

Is realistic neuronal modeling realistic?

PubMed Central

Almog, Mara

2016-01-01

Scientific models are abstractions that aim to explain natural phenomena. A successful model shows how a complex phenomenon arises from relatively simple principles while preserving major physical or biological rules and predicting novel experiments. A model should not be a facsimile of reality; it is an aid for understanding it. Contrary to this basic premise, with the 21st century has come a surge in computational efforts to model biological processes in great detail. Here we discuss the oxymoronic, realistic modeling of single neurons. This rapidly advancing field is driven by the discovery that some neurons don't merely sum their inputs and fire if the sum exceeds some threshold. Thus researchers have asked what are the computational abilities of single neurons and attempted to give answers using realistic models. We briefly review the state of the art of compartmental modeling highlighting recent progress and intrinsic flaws. We then attempt to address two fundamental questions. Practically, can we realistically model single neurons? Philosophically, should we realistically model single neurons? We use layer 5 neocortical pyramidal neurons as a test case to examine these issues. We subject three publically available models of layer 5 pyramidal neurons to three simple computational challenges. Based on their performance and a partial survey of published models, we conclude that current compartmental models are ad hoc, unrealistic models functioning poorly once they are stretched beyond the specific problems for which they were designed. We then attempt to plot possible paths for generating realistic single neuron models. PMID:27535372

Comparison of the influence of two models of mild stress on hippocampal brain-derived neurotrophin factor (BDNF) immunoreactivity in old age rats.

PubMed

Badowska-Szalewska, Ewa; Ludkiewicz, Beata; Krawczyk, Rafał; Melka, Natalia; Moryś, Janusz

2017-01-01

The way hippocampal neurons function during stress in old age (critical times of life) is dependent on brain derived neurotrophin factor (BDNF). This study examined the influence of acute and chronic forced swim (FS) or high-light open field (HL‑OF) stimulation on the density of BDNF immunoreactive (ir) neurons in the hippocampal pyramidal layers of CA1, CA2, CA3 regions and the granular layer of dentate gyrus (DG) in old (postnatal day 720; P720) Wistar Han rats. Our data showed that in comparison with non-stressed rats, acute FS caused a significant increase in the density of BDNF-ir neurons in CA2 and CA3, while acute HL-OF led to an increase in this factor in all hippocampal subfields with the exception of DG. However, the density of BDNF-ir cells remained unchanged after exposure to chronic FS or HL‑OF in the hippocampal regions in relation to the control rats. These results indicate that acute FS or HL-OF proved to be a stressor that induces an increase in the density of BDNF-ir pyramidal neurons, which was probably connected with up-regulation of HPA axis activity and short‑time memory processing of the stressful situation. Moreover, as far as the influence on BDNF-ir cells in hippocampus is concerned, chronic FS or HL-OF was not an aggravating factor for rats in the ontogenetic periods studied.

Teacher Acquisition of Functional Analysis Methods Using Pyramidal Training

ERIC Educational Resources Information Center

Pence, Sacha T.; St. Peter, Claire C.; Giles, Aimee F.

2014-01-01

Pyramidal training involves an experienced professional training a subset of individuals who, in turn, train additional individuals. Pyramidal training is effective for training a variety of behavior-analytic skills with direct-care staff, parents, and teachers. As teachers' roles in behavioral assessment increase, pyramidal training may be…

Mechanism of selenite removal by a mixed adsorbent based on Fe-Mn hydrous oxides studied using X-ray absorption spectroscopy.

PubMed

Chubar, Natalia; Gerda, Vasyl; Szlachta, Małgorzata

2014-11-18

Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3(2-) trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

I-III-VI.sub.2 based solar cell utilizing the structure CuInGaSe.sub.2 CdZnS/ZnO

DOEpatents

Chen, Wen S.; Stewart, John M.

1992-01-07

A thin film I-III-VI.sub.2 based solar cell having a first layer of copper indium gallium selenide, a second layer of cadmium zinc sulfide, a double layer of zinc oxide, and a metallization structure comprised of a layer of nickel covered by a layer of aluminum. An optional antireflective coating may be placed on said metallization structure. The cadmium zinc sulfide layer is deposited by means of an aqueous solution growth deposition process and may actually consist of two layers: a low zinc content layer and a high zinc content layer. Photovoltaic efficiencies of 12.5% at Air Mass 1.5 illumination conditions and 10.4% under AMO illumination can be achieved.

The Learning Pyramid: Does It Point Teachers in the Right Direction?

ERIC Educational Resources Information Center

Lalley, James P.; Miller, Robert H.

2007-01-01

This paper raises serious questions about the reliability of the learning pyramid as a guide to retention among students. The pyramid suggests that certain teaching methods are connected with a corresponding hierarchy of student retention. No specific credible research was uncovered to support the pyramid, which is loosely associated with the…

Effect of housing rats within a pyramid on stress parameters.

PubMed

Bhat, Surekha; Rao, Guruprasad; Murthy, K Dilip; Bhat, P Gopalakrishna

2003-11-01

The Giza pyramids of Egypt have been the subject of much research. Pyramid models with the same base to height ratio as of the Great Pyramid of Giza, when aligned on a true north-south axis, are believed to generate, transform and transmit energy. Research done with such pyramid models has shown that they induced greater relaxation in human subjects, promoted better wound healing in rats and afforded protection against stress-induced neurodegnerative changes in mice. The present study was done to assess the effects of housing Wistar rats within the pyramid on the status of oxidative damage and antioxidant defense in their erythrocytes and cortisol levels in their plasma. Rats were housed in cages under standard laboratory conditions. Cages were left in the open (normal control), under a wooden pyramid model (experimental rats) or in a cubical box of comparable dimensions (6 hr/day for 14 days). Erythrocyte malondialdehyde and plasma cortisol levels were significantly decreased in rats kept within the pyramid as compared to the normal control and those within the square box. Erythrocyte reduced glutathione levels, erythrocyte glutathione peroxidase and superoxide dismutase activities were significantly increased in the rats kept in the pyramid as compared to the other two groups. There was no significant difference in any of the parameters between the normal control and rats kept in the square box. The results showed that exposure of adult female Wistar rats to pyramid environment reduces stress oxidative stress and increases antioxidant defense in them.

Improvement of the recombination and infrared light losses by rear surface chemical polishing in silicon heterojunction solar cells

NASA Astrophysics Data System (ADS)

Yang, Xueliang; Zhang, Yi; Li, Feng; Sun, Yun

2017-06-01

Rear surface chemical polishing (RSCP) was investigated for the improvement of the internal reflection and surface passivation of heterojunction solar cells with intrinsic thin layers (HIT). The HIT solar cells without or with RSCP treatment were prepared by plasma-enhanced chemical vapor deposition and physical vapor deposition techniques. Scanning electron microscopy results showed that rounding of the spires and V-groove bottom of the pyramid as well as smoothing of incline surface of the pyramid were achieved. These effects would decrease the loss of infrared light transmittance and interface recombination at the rear surface of the cells. To experimentally corroborate these two points, two special geometries, ITO/c-Si/hydrogenated amorphous silicon (a-Si:H)/ITO and a-Si:H/c-Si/a-Si:H, were introduced as a test of the reflectance/transmittance spectra and the minority carrier lifetime. Weakened transmittance and enhanced lifetime were observed for the sample with RSCP, which are responsible for the improvement of J sc and V oc, respectively. Therefore, RSCP is a promising candidate for improving the performance of HIT solar cells.

Isolated Mesoporous Microstructures Prepared by Stress Localization-Induced Crack Manipulation.

PubMed

Wooh, Sanghyuk; Lee, Soojin; Lee, Yunchan; Ryu, Ji Ho; Lee, Won Bo; Yoon, Hyunsik; Char, Kookheon

2016-09-22

Cracks observed in brittle materials are mostly regarded as defects or failures. However, they can be a valuable tool when implemented in a controlled way. Here, we introduce a strategy to control the crack propagation of mesoporous micropatterns (prisms and pyramids), which leads to the isolation of well-defined microstructures. Mesoporous micropatterns were fabricated by the soft imprinting technique with wet TiO 2 nanoparticle (NP) pastes, followed by sintering to remove organic components. Since the volume of the paste significantly shrinks during the sintering step, stress is localized at the edge of micropatterns, in good agreement with finite element method simulations, creating well-defined cracks and their propagation. It was demonstrated that the degree of stress localization is determined by the thickness of residual layers, NP size, and heating rate. After controlled crack propagation and delamination of microparticles from the substrates, mesoporous microwires and microparticles were successfully produced and functionalized from the isolated mesoporous prisms and pyramids. The method proposed in this study for controlled crack manipulation and delamination opens a door for straightforward and economical fabrication of well-defined mesoporous microparticles.

An optimized fluorescent probe for visualizing glutamate neurotransmission.

PubMed

Marvin, Jonathan S; Borghuis, Bart G; Tian, Lin; Cichon, Joseph; Harnett, Mark T; Akerboom, Jasper; Gordus, Andrew; Renninger, Sabine L; Chen, Tsai-Wen; Bargmann, Cornelia I; Orger, Michael B; Schreiter, Eric R; Demb, Jonathan B; Gan, Wen-Biao; Hires, S Andrew; Looger, Loren L

2013-02-01

We describe an intensity-based glutamate-sensing fluorescent reporter (iGluSnFR) with signal-to-noise ratio and kinetics appropriate for in vivo imaging. We engineered iGluSnFR in vitro to maximize its fluorescence change, and we validated its utility for visualizing glutamate release by neurons and astrocytes in increasingly intact neurological systems. In hippocampal culture, iGluSnFR detected single field stimulus-evoked glutamate release events. In pyramidal neurons in acute brain slices, glutamate uncaging at single spines showed that iGluSnFR responds robustly and specifically to glutamate in situ, and responses correlate with voltage changes. In mouse retina, iGluSnFR-expressing neurons showed intact light-evoked excitatory currents, and the sensor revealed tonic glutamate signaling in response to light stimuli. In worms, glutamate signals preceded and predicted postsynaptic calcium transients. In zebrafish, iGluSnFR revealed spatial organization of direction-selective synaptic activity in the optic tectum. Finally, in mouse forelimb motor cortex, iGluSnFR expression in layer V pyramidal neurons revealed task-dependent single-spine activity during running.

Expression of Kv3.1b potassium channel is widespread in macaque motor cortex pyramidal cells: A histological comparison between rat and macaque.

PubMed

Soares, David; Goldrick, Isabelle; Lemon, Roger N; Kraskov, Alexander; Greensmith, Linda; Kalmar, Bernadett

2017-06-15

There are substantial differences across species in the organization and function of the motor pathways. These differences extend to basic electrophysiological properties. Thus, in rat motor cortex, pyramidal cells have long duration action potentials, while in the macaque, some pyramidal neurons exhibit short duration "thin" spikes. These differences may be related to the expression of the fast potassium channel Kv3.1b, which in rat interneurons is associated with generation of thin spikes. Rat pyramidal cells typically lack these channels, while there are reports that they are present in macaque pyramids. Here we made a systematic, quantitative comparison of the Kv3.1b expression in sections from macaque and rat motor cortex, using two different antibodies (NeuroMab, Millipore). As our standard reference, we examined, in the same sections, Kv3.1b staining in parvalbumin-positive interneurons, which show strong Kv3.1b immunoreactivity. In macaque motor cortex, a large sample of pyramidal neurons were nearly all found to express Kv3.1b in their soma membranes. These labeled neurons were identified as pyramidal based either by expression of SMI32 (a pyramidal marker), or by their shape and size, and lack of expression of parvalbumin (a marker for some classes of interneuron). Large (Betz cells), medium, and small pyramidal neurons all expressed Kv3.1b. In rat motor cortex, SMI32-postive pyramidal neurons expressing Kv3.1b were very rare and weakly stained. Thus, there is a marked species difference in the immunoreactivity of Kv3.1b in pyramidal neurons, and this may be one of the factors explaining the pronounced electrophysiological differences between rat and macaque pyramidal neurons. © 2017 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

Static Posturography and Falls According to Pyramidal, Sensory and Cerebellar Functional Systems in People with Multiple Sclerosis

PubMed Central

Kalron, Alon; Givon, Uri; Frid, Lior; Dolev, Mark; Achiron, Anat

2016-01-01

Balance impairment is common in people with multiple sclerosis (PwMS) and frequently impacts quality of life by decreasing mobility and increasing the risk of falling. However, there are only scarce data examining the contribution of specific neurological functional systems on balance measures in MS. Therefore, the primary aim of our study was to examine the differences in posturography parameters and fall incidence according to the pyramidal, cerebellar and sensory systems functional systems in PwMS. The study included 342 PwMS, 211 women and mean disease duration of 8.2 (S.D = 8.3) years. The study sample was divided into six groups according to the pyramidal, cerebellar and sensory functional system scores, derived from the Expanded Disability Status Scale (EDSS) data. Static postural control parameters were obtained from the Zebris FDM-T Treadmill (zebris® Medical GmbH, Germany). Participants were defined as "fallers" and "non-fallers" based on their fall history. Our findings revealed a trend that PwMS affected solely in the pyramidal system, have reduced stability compared to patients with cerebellar and sensory dysfunctions. Moreover, the addition of sensory impairments to pyramidal dysfunction does not exacerbate postural control. The patients in the pure sensory group demonstrated increased stability compared to each of the three combined groups; pyramidal-cerebellar, pyramidal-sensory and pyramidal-cerebellar-sensory groups. As for fall status, the percentage of fallers in the pure pyramidal, cerebellar and sensory groups were 44.3%, 33.3% and 19.5%, respectively. As for the combined functional system groups, the percentage of fallers in the pyramidal-cerebellar, pyramidal-sensory and pyramidal-cerebellar-sensory groups were 59.7%, 40.7% and 65%, respectively. This study confirms that disorders in neurological functional systems generate different effects on postural control and incidence of falls in the MS population. From a clinical standpoint, the present information can benefit all those engaged in physical rehabilitation of PwMS. PMID:27741268

Idea Bank: Assessing Your Curriculum with the Creative Rights Pyramid

ERIC Educational Resources Information Center

Thibeault, Matthew D.

2011-01-01

This article presents a creative rights pyramid that was developed as part of the author's efforts to: (1) teach about copyright and intellectual property; and (2) increase students' awareness of their own intellectual property in and outside the music classroom. The pyramid is based on the U.S. Department of Agriculture's food pyramid to suggest…

Using the Food Guide Pyramid: A Resource for Nutrition Educators.

ERIC Educational Resources Information Center

Shaw, Anne; Fulton, Lois; Davis, Carole; Hogbin, Myrtle

This booklet provides information to assist nutrition educators in helping their audiences use the Food Guide Pyramid to plan and prepare foods for a healthy diet. It reviews the objectives set in developing the Food Guide Pyramid and illustrates their impact on the application of the Food Guide Pyramid to planning menus. In particular, the…

[Morphological changes of neurons and neuroglial cells in the brain of senescence-accelerated prone 1 (SAMP1) mice].

PubMed

Khudoerkov, R M; Sal'kov, V N; Sal'nikova, O V; Sobolev, V B

2014-01-01

Computerized morphometry was used to examine the sizes of neuronal bodies and the compactness of arrangement of neurons and neuroglial cells in layers III and V of the sensorimotor cortex in senescence-accelerated prone 1 (SAMP1) mice (an experimental group) and senescence-accelerated-resistant strain 1 (SAMR1) ones (a control group). In the SAMP1 mice as compared to the SAMR1 ones, the neuronal body sizes were significantly unchanged; the compactness of their arrangement decreased by 17 and 20% in layers III and V, respectively; that of neuroglial cells significantly increased by 14% in layer III only. In the SAMP1 mice versus the SAMR1 ones, the glial index rose by 36% in layer III and by 24% in layer V. During simulation of physiological aging, the sizes of neuronal bodies were shown to be virtually unchanged in the cerebral cortex; the compactness of their arrangement (cell counts) moderately reduced and that of neuroglial cells increased, which caused a rise in the glioneuronal index that was indicative of the enhanced supporting function of neuroglial cells during the physiological aging of brain structures.

Relevance of the pyramidal syndrome in amyotrophic lateral sclerosis.

PubMed

Álvarez, N; Díez, L; Avellaneda, C; Serra, M; Rubio, M Á

Pyramidal signs (hyperreflexia, spasticity, Babinski sign) are essential for the diagnosis of amyotrophic lateral sclerosis (ALS). However, these signs are not always present at onset and may vary over time, besides which their role in disease evolution is controversial. Our goal was to describe which pyramidal signs were present and how they evolved in a cohort of patients with ALS, as well as their role in prognosis. Retrospective analysis of prospectively collected patients diagnosed with ALS in our centre from 1990 to 2015. Of a total of 130 patients with ALS, 34 (26.1%) patients showed no pyramidal signs at the first visit while 15 (11.5%) had a complete pyramidal syndrome. Of those patients without initial pyramidal signs, mean time of appearance of the first signs was 4.5 months. Babinski sign was positive in 64 (49.2%) patients, hyperreflexia in 90 (69.2%) and 22 (16.9%) patients had spasticity. Pyramidal signs tended to remain unchanged over time, although they seem to appear at later stages or even disappear with time in some patients. We found no association between survival and the presence of changes to pyramidal signs, although decreased spasticity was associated with greater clinical deterioration (ALSFR scale) (P<.001). A quarter of patients with ALS initially showed no pyramidal signs and in some cases they even disappear over time. These data support the need for tools that assess the pyramidal tract. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

Effect of in situ annealing on the structural and electrical properties and infrared photodetection of III-Sb on GaAs using interfacial misfit array

NASA Astrophysics Data System (ADS)

Jia, Bo Wen; Tan, Kian Hua; Loke, Wan Khai; Wicaksono, Satrio; Yoon, Soon Fatt

2018-01-01

This work presents the effects of in situ thermal annealing under antimony overpressure on the structural, electrical, and optical properties of III-Sb (GaSb and InSb) grown on (100) GaAs using an interfacial misfit array to accommodate the lattice mismatch. Both the sample growth and the in situ thermal annealing were carried out in the in the molecular beam epitaxy system, and the temperature of the as-grown sample was increased to exceed its growth temperature during the annealing. X-ray diffraction demonstrates nearly fully relaxed as-grown and annealed III-Sb layers. The optimal annealing temperatures and durations are for 590 °C, 5 min for GaSb and 420 °C, 15 min for InSb, respectively. In situ annealing decreased the surface roughness of the III-Sb layers. X-ray reciprocal space mapping and transmission electron microscopy observation showed stable interfacial misfit arrays, and no interfacial diffusion occurred in the annealed III-Sb layers. A Hall measurement of unintentionally doped III-Sb layers showed greater carrier mobility and a lower carrier concentration in the annealed samples at both 77 and 300 K. In situ annealing improved the photoresponsivity of GaSb and InSb photoconductors grown on GaAs in the near- and mid-infrared ranges, respectively.

Distinct interneuron types express m2 muscarinic receptor immunoreactivity on their dendrites or axon terminals in the hippocampus.

PubMed

Hájos, N; Papp, E C; Acsády, L; Levey, A I; Freund, T F

1998-01-01

In previous studies m2 muscarinic acetylcholine receptor-immunoreactive interneurons and various types of m2-positive axon terminals have been described in the hippocampal formation. The aim of the present study was to identify the types of interneurons expressing m2 receptor and to examine whether the somadendritic and axonal m2 immunostaining labels the same or distinct cell populations. In the CA1 subfield, neurons immunoreactive for m2 have horizontal dendrites, they are located at the stratum oriens/alveus border and have an axon that project to the dendritic region of pyramidal cells. In the CA3 subfield and the hilus, m2-positive neurons are multipolar and are scattered in all layers except stratum lacunosum-moleculare. In stratum pyramidale of the CA1 and CA3 regions, striking axon terminal staining for m2 was observed, surrounding the somata and axon initial segments of pyramidal cells in a basket-like manner. The co-localization of m2 with neurochemical markers and GABA was studied using the "mirror" technique and fluorescent double-immunostaining at the light microscopic level and with double-labelling using colloidal gold-conjugated antisera and immunoperoxidase reaction (diaminobenzidine) at the electron microscopic level. GABA was shown to be present in the somata of most m2-immunoreactive interneurons, as well as in the majority of m2-positive terminals in all layers. The calcium-binding protein parvalbumin was absent from practically all m2-immunoreactive cell bodies and dendrites. In contrast, many of the terminals synapsing on pyramidal cell somata and axon initial segments co-localized parvalbumin and m2, suggesting a differential distribution of m2 receptor immunoreactivity on the axonal and somadendritic membrane of parvalbumin-containing basket and axo-axonic cells. The co-existence of m2 receptors with the calcium-binding protein calbindin and the neuropeptides cholecystokinin and vasoactive intestinal polypeptide was rare throughout the hippocampal formation. Only calretinin and somatostatin showed an appreciable degree of co-localization with m2 (20% and 15%, respectively). Using retrograde tracing, some of the m2-positive cells in stratum oriens were shown to project to the medial septum, accouting for 38% of all projection neurons. The present results demonstrate that there is a differential distribution of m2 receptor immunoreactivity on the axonal vs the somadendritic membranes of distinct interneuron types and suggest that acetylcholine via m2 receptors may reduce GABA release presynaptically from the terminals of perisomatic inhibitory cells, while it may act to increase the activity of another class of interneuron, which innervates the dendritic region of pyramidal cells.

Palladium-catalyzed cocyclotrimerization of arynes with a pyramidalized alkene.

PubMed

Alonso, José M; Quiroga, Sabela; Codony, Sandra; Turcu, Andreea L; Barniol-Xicota, Marta; Pérez, Dolores; Guitián, Enrique; Vázquez, Santiago; Peña, Diego

2018-05-23

The metal-catalyzed [2+2+2] cocycloaddition of arynes with pyramidalized alkenes is presented. The generation of a highly reactive pyramidalized alkene in the presence of a large excess of in situ-produced arynes led to the corresponding cocyclotrimerization (1 : 2)-adducts in good yields, establishing the first example of a palladium-based reaction of a pyramidalized alkene.

[Pyramidal syndrome in lateral amyotrophic sclerosis: clinico-morphological analysis].

PubMed

Musaeva, L S; Zavalishin, I A; Gulevskaia, T S

2003-01-01

Retrospective clinical analysis with a special focus on pyramidal syndrome expression in the disease course as well as morphological study of brain and spinal structures in all levels of cortical-spinal projection (from brain motor cortex to spinal lumbar segments) have been conducted for 11 section cases of lateral amyotrophic sclerosis (LAS), sporadic type. Two groups of patients were studied: with pronounced pyramidal syndrome (spasticity, hyperreflexia, etc)--7 cases and with some signs of pyramidal deficiency (anisoreflexia, stability of peritoneal reflexes)--4 cases. Pyramidal syndrome in LAS is considered as an emergence of current neurodegenerative process, embracing a significant part of upper motor neurons of both precentral convolution and its axons along the whole length of cerebrospinal axis in the form of cytoplasmic inclusions and axonal spheroids. A presence of pathomorphological changes in other upper segmental structures of motor control reveals their role in pyramidal deficiency. Comparative analysis showed that expression of pyramidal syndrome signs and its correlation to atrophic paresis appearances is specifically determined by the severity of upper and lower motor neurons lesions. With regard to morphological changes in CNS structures, the peculiarities of some pyramidal syndrome appearances in LAS are analyzed.

Coordination polyhedron and chemical vapor deposition of Cu(hfacac)2(t-BuNH2).

PubMed

Woo, Kyoungja; Paek, Hojeong; Lee, Wan In

2003-10-06

A new pentacoordinate Cu(II) complex, Cu(hfacac)(2)(t-BuNH(2)) [hfacac = CF(3)C(O)CHC(O)CF(3)(-), t-BuNH(2) = tert-butylamine], has been synthesized and structurally characterized. Interestingly, the structure of a single crystal occurred as square pyramidal with one O atom at the apical position and one N and three O atoms at the basal positions, showing a serious degree of distortion. This contrasts with the square-pyramidal structure of Cu(hfacac)(2)L (L = H(2)O and pyrazine), which has the L ligand at the axial position. In the Cu(hfacac)(2)(t-BuNH(2)) complex, the t-BuNH(2) ligand is placed at an equatorial position with a lowered angle by 19.9(2) degrees from the basal plane. This distortion seems to reduce sigma influence and steric hindrance and so stabilizes the square-pyramidal geometry. This precursor has a lower melting point and superior stability to air, moisture, and heat than the Cu(hfacac)(2)(xH(2)O) precursor. The deposition rate of copper oxide film on a Pt layer above 450 degrees C was nearly constant with increasing temperature, indicating a mass transport limited reaction. Therefore it would be a useful metal organic chemical vapor deposition precursor for the fabrication of copper oxide film or superconducting materials. Crystal data for Cu(hfacac)(2)(t-BuNH(2)): 293(2) K, a = 9.6699(4) A, b = 18.0831(10) A, c = 12.8864(11) A, beta = 111.839(5) degrees, monoclinic, space group P2(1)/c, Z = 4.

Variant BDNF-Val66Met Polymorphism is Associated with Layer-Specific Alterations in GABAergic Innervation of Pyramidal Neurons, Elevated Anxiety and Reduced Vulnerability of Adolescent Male Mice to Activity-Based Anorexia.

PubMed

Chen, Yi-Wen; Surgent, Olivia; Rana, Barkha S; Lee, Francis; Aoki, Chiye

2017-08-01

Previously, we determined that rodents' vulnerability to food restriction (FR)-evoked wheel running during adolescence (activity-based anorexia, ABA) is associated with failures to increase GABAergic innervation of hippocampal and medial prefrontal pyramidal neurons. Since brain-derived neurotrophic factor (BDNF) promotes GABAergic synaptogenesis, we hypothesized that individual differences in this vulnerability may arise from differences in the link between BDNF bioavailability and FR-evoked wheel running. We tested this hypothesis in male BDNF-Val66Met knock-in mice (BDNFMet/Met), known for reduction in the activity-dependent BDNF secretion and elevated anxiety-like behaviors. We found that 1) in the absence of FR or a wheel (i.e., control), BDNFMet/Met mice are more anxious than wild-type (WT) littermates, 2) electron microscopically verified GABAergic innervations of pyramidal neurons of BDNFMet/Met mice are reduced at distal dendrites in hippocampal CA1 and medial prefrontal cortex, 3) following ABA, WT mice exhibit anxiety equal to those of the BDNFMet/Met mice and have lost GABAergic innervation along distal dendrites, 4) BDNFMet/Met mice show blunted ABA vulnerability, and 5) unexpectedly, GABAergic innervation is higher at somata of BDNFMet/Met mice than of WT. We conclude that lamina-specific GABAergic inhibition is important for regulating anxiety, whether arising from environmental stress, such as food deprivation, or genetically, such as BDNFMet/Met single nucleotide polymorphism. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Branching angles of pyramidal cell dendrites follow common geometrical design principles in different cortical areas.

PubMed

Bielza, Concha; Benavides-Piccione, Ruth; López-Cruz, Pedro; Larrañaga, Pedro; DeFelipe, Javier

2014-08-01

Unraveling pyramidal cell structure is crucial to understanding cortical circuit computations. Although it is well known that pyramidal cell branching structure differs in the various cortical areas, the principles that determine the geometric shapes of these cells are not fully understood. Here we analyzed and modeled with a von Mises distribution the branching angles in 3D reconstructed basal dendritic arbors of hundreds of intracellularly injected cortical pyramidal cells in seven different cortical regions of the frontal, parietal, and occipital cortex of the mouse. We found that, despite the differences in the structure of the pyramidal cells in these distinct functional and cytoarchitectonic cortical areas, there are common design principles that govern the geometry of dendritic branching angles of pyramidal cells in all cortical areas.

Branching angles of pyramidal cell dendrites follow common geometrical design principles in different cortical areas

PubMed Central

Bielza, Concha; Benavides-Piccione, Ruth; López-Cruz, Pedro; Larrañaga, Pedro; DeFelipe, Javier

2014-01-01

Unraveling pyramidal cell structure is crucial to understanding cortical circuit computations. Although it is well known that pyramidal cell branching structure differs in the various cortical areas, the principles that determine the geometric shapes of these cells are not fully understood. Here we analyzed and modeled with a von Mises distribution the branching angles in 3D reconstructed basal dendritic arbors of hundreds of intracellularly injected cortical pyramidal cells in seven different cortical regions of the frontal, parietal, and occipital cortex of the mouse. We found that, despite the differences in the structure of the pyramidal cells in these distinct functional and cytoarchitectonic cortical areas, there are common design principles that govern the geometry of dendritic branching angles of pyramidal cells in all cortical areas. PMID:25081193

Structure resolution by electron diffraction tomography of the complex layered iron-rich Fe-2234-type Sr{sub 5}Fe{sub 6}O{sub 15.4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lepoittevin, Christophe, E-mail: christophe.lepoittevin@neel.cnrs.fr

2016-10-15

The crystal structure of the strontium ferrite Sr{sub 5}Fe{sub 6}O{sub 15.4}, was solved by direct methods on electron diffraction tomography data acquired on a transmission electron microscope. The refined cell parameters are a=27.4047(3) Å, b=5.48590(7) Å and c=42.7442(4) Å in Fm2m symmetry. Its structure is built up from the intergrowth sequence between a quadruple perovskite-type layer with a complex rock-salt (RS)-type block. In the latter iron atoms are found in two different environments : tetragonal pyramid and tetrahedron. The structural model was refined by Rietveld method based on the powder X-ray diffraction pattern. - Highlights: • Complex structure of Sr{submore » 5}Fe{sub 6}O{sub 15.4} solved by electron diffraction tomography. • Observed Fourier maps allow determining missing oxygen atoms in the structure. • Structural model refined from powder X-ray diffraction data. • Intergrowth between quadruple perovskite layer with double rock-salt-type layer.« less

Virtual pyramid wavefront sensor for phase unwrapping.

PubMed

Akondi, Vyas; Vohnsen, Brian; Marcos, Susana

2016-10-10

Noise affects wavefront reconstruction from wrapped phase data. A novel method of phase unwrapping is proposed with the help of a virtual pyramid wavefront sensor. The method was tested on noisy wrapped phase images obtained experimentally with a digital phase-shifting point diffraction interferometer. The virtuality of the pyramid wavefront sensor allows easy tuning of the pyramid apex angle and modulation amplitude. It is shown that an optimal modulation amplitude obtained by monitoring the Strehl ratio helps in achieving better accuracy. Through simulation studies and iterative estimation, it is shown that the virtual pyramid wavefront sensor is robust to random noise.

Pyramid beam splitter

DOEpatents

McKeown, Mark H.; Beason, Steven C.; Fairer, George

1992-01-01

The apparatus of the present invention provides means for obtaining accurate, dependable, measurement of bearings and directions for geologic mapping in subterranean shafts, such as, for example, nuclear waste storage investigations. In operation, a laser beam is projected along a reference bearing. A pyramid is mounted such that the laser beam is parallel to the pyramid axis and can impinge on the apex of the pyramid thus splitting the beam several ways into several beams at right angles to each other and at right angles to the reference beam. The pyramid is also translatable and rotatable in a plane perpendicular to the reference beam.

Synthesis, spectroscopic, photoluminescence properties and biological evaluation of novel Zn(II) and Al(III) complexes of NOON tetradentate Schiff bases

NASA Astrophysics Data System (ADS)

Abdel Aziz, Ayman A.; Badr, Ibrahim H. A.; El-Sayed, Ibrahim S. A.

2012-11-01

Novel mononuclear Zn(II) and Al(III) complexes were synthesized from the reactions of Zn(OAc)2·2H2O and anhydrous AlCl3 with neutral N2O2 donor tetradentate Schiff bases; N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H2L1) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2L2). The new complexes were fully characterized by using micro analyses (CHN), FT-IR, 1H NMR, UV-Vis spectra and thermal analysis. The analytical data have been showed that, the stoichiometry of the complexes is 1:1. Spectroscopic data suggested tetrahedral and square pyramidal geometries for Zn(II) and Al(III) complexes, respectively. The synthesized Zn(II), and Al(III) complexes exhibited intense fluorescence emission in the visible region upon UV-excitation in methylene chloride solution at ambient temperature. This high fluorescence emission was assigned to the strong coordination of the ligands to the small and the highly charged Zn(II) and Al(III) ions. Such strong coordination seems to extend the π-conjugation of the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. As a potential application the biological activity (e.g., antimicrobial action) of the prepared ligands and complexes was assessed by in-vitro testing of their effect on the growth of various strains of bacteria and fungi.

Syntheses and characterization of one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yohannan, Jinu P.; Vidyasagar, Kanamaluru, E-mail: kvsagar@iitm.ac.in

2015-01-15

Three new isostructural quaternary antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) have been synthesized by using alkali metal thiosulfate flux and structurally characterized by X-ray diffraction. Their structures contain A{sup +} ions around the [Sb{sub 2}Sn{sub 3}S{sub 10}]{sup 2−} chains, which are built from SbS{sub 3} pyramids, SnS{sub 6} octahedra and SnS{sub 4} tetrahedra. Raman and Mössbauer spectroscopic measurements corroborate the oxidation states and coordination environments of Sb(III) and Sn(IV). All three compounds are wide band gap semiconductors. Potassium compound undergoes partial exchange with strontium, cadmium and lead ions. - Graphical abstract: Syntheses, crystal structure, spectroscopic andmore » partial ion-exchange studies of new one-dimensional alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs) are described. - Highlights: • Syntheses of new alkali metal antimony(III) thiostannates(IV), A{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} (A=K, Rb, Cs). • Wide band gap semiconductors with one-dimensional structure. • Topotactic partial exchange of K{sup +} ions of K{sub 2}Sb{sub 2}Sn{sub 3}S{sub 10} with Sr{sup 2+}, Cd{sup 2+} and Pb{sup 2+} ions.« less

Synthesis, spectroscopic, photoluminescence properties and biological evaluation of novel Zn(II) and Al(III) complexes of NOON tetradentate Schiff bases.

PubMed

Abdel Aziz, Ayman A; Badr, Ibrahim H A; El-Sayed, Ibrahim S A

2012-11-01

Novel mononuclear Zn(II) and Al(III) complexes were synthesized from the reactions of Zn(OAc)(2).2H(2)O and anhydrous AlCl(3) with neutral N2O2 donor tetradentate Schiff bases; N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H(2)L(1)) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H(2)L(2)). The new complexes were fully characterized by using micro analyses (CHN), FT-IR, (1)H NMR, UV-Vis spectra and thermal analysis. The analytical data have been showed that, the stoichiometry of the complexes is 1:1. Spectroscopic data suggested tetrahedral and square pyramidal geometries for Zn(II) and Al(III) complexes, respectively. The synthesized Zn(II), and Al(III) complexes exhibited intense fluorescence emission in the visible region upon UV-excitation in methylene chloride solution at ambient temperature. This high fluorescence emission was assigned to the strong coordination of the ligands to the small and the highly charged Zn(II) and Al(III) ions. Such strong coordination seems to extend the π-conjugation of the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. As a potential application the biological activity (e.g., antimicrobial action) of the prepared ligands and complexes was assessed by in-vitro testing of their effect on the growth of various strains of bacteria and fungi. Copyright © 2012 Elsevier B.V. All rights reserved.

Magnetic susceptibility and ground-state zero-field splitting in high-spin mononuclear manganese(III) of inverted N-methylated porphyrin complexes: Mn(2-NCH3NCTPP)Br.

PubMed

Hung, Sheng-Wei; Yang, Fuh-An; Chen, Jyh-Horung; Wang, Shin-Shin; Tung, Jo-Yu

2008-08-18

The crystal structures of diamagnetic dichloro(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N'')-tin(IV) methanol solvate [Sn(2-NCH 3NCTPP)Cl 2.2(0.2MeOH); 6.2(0.2MeOH)] and paramagnetic bromo(2-aza-2-methyl-5,10,15,20-tetraphenyl-21-carbaporphyrinato-N,N',N'')-manganese(III) [Mn(2-NCH 3NCTPP)Br; 5] were determined. The coordination sphere around Sn (4+) in 6.2(0.2MeOH) is described as six-coordinate octahedron ( OC-6) in which the apical site is occupied by two transoid Cl (-) ligands, whereas for the Mn (3+) ion in 5, it is a five-coordinate square pyramid ( SPY-5) in which the unidentate Br (-) ligand occupies the axial site. The g value of 9.19 (or 10.4) measured from the parallel polarization (or perpendicular polarization) of X-band EPR spectra at 4 K is consistent with a high spin mononuclear manganese(III) ( S = 2) in 5. The magnitude of axial ( D) and rhombic ( E) zero-field splitting (ZFS) for the mononuclear Mn(III) in 5 were determined approximately as -2.4 cm (-1) and -0.0013 cm (-1), respectively, by paramagnetic susceptibility measurements and conventional EPR spectroscopy. Owing to weak C(45)-H(45A)...Br(1) hydrogen bonds, the mononuclear Mn(III) neutral molecules of 5 are arranged in a one-dimensional network. A weak Mn(III)...Mn(III) ferromagnetic interaction ( J = 0.56 cm (-1)) operates via a [Mn(1)-C(2)-C(1)-N(4)-C(45)-H(45A)...Br(1)-Mn(1)] superexchange pathway in complex 5.

Autosomal dominant cerebellar ataxia type III: a review of the phenotypic and genotypic characteristics.

PubMed

Fujioka, Shinsuke; Sundal, Christina; Wszolek, Zbigniew K

2013-01-18

Autosomal Dominant Cerebellar Ataxia (ADCA) Type III is a type of spinocerebellar ataxia (SCA) classically characterized by pure cerebellar ataxia and occasionally by non-cerebellar signs such as pyramidal signs, ophthalmoplegia, and tremor. The onset of symptoms typically occurs in adulthood; however, a minority of patients develop clinical features in adolescence. The incidence of ADCA Type III is unknown. ADCA Type III consists of six subtypes, SCA5, SCA6, SCA11, SCA26, SCA30, and SCA31. The subtype SCA6 is the most common. These subtypes are associated with four causative genes and two loci. The severity of symptoms and age of onset can vary between each SCA subtype and even between families with the same subtype. SCA5 and SCA11 are caused by specific gene mutations such as missense, inframe deletions, and frameshift insertions or deletions. SCA6 is caused by trinucleotide CAG repeat expansions encoding large uninterrupted glutamine tracts. SCA31 is caused by repeat expansions that fall outside of the protein-coding region of the disease gene. Currently, there are no specific gene mutations associated with SCA26 or SCA30, though there is a confirmed locus for each subtype. This disease is mainly diagnosed via genetic testing; however, differential diagnoses include pure cerebellar ataxia and non-cerebellar features in addition to ataxia. Although not fatal, ADCA Type III may cause dysphagia and falls, which reduce the quality of life of the patients and may in turn shorten the lifespan. The therapy for ADCA Type III is supportive and includes occupational and speech modalities. There is no cure for ADCA Type III, but a number of recent studies have highlighted novel therapies, which bring hope for future curative treatments.

Autosomal dominant cerebellar ataxia type III: a review of the phenotypic and genotypic characteristics

PubMed Central

2013-01-01

Autosomal Dominant Cerebellar Ataxia (ADCA) Type III is a type of spinocerebellar ataxia (SCA) classically characterized by pure cerebellar ataxia and occasionally by non-cerebellar signs such as pyramidal signs, ophthalmoplegia, and tremor. The onset of symptoms typically occurs in adulthood; however, a minority of patients develop clinical features in adolescence. The incidence of ADCA Type III is unknown. ADCA Type III consists of six subtypes, SCA5, SCA6, SCA11, SCA26, SCA30, and SCA31. The subtype SCA6 is the most common. These subtypes are associated with four causative genes and two loci. The severity of symptoms and age of onset can vary between each SCA subtype and even between families with the same subtype. SCA5 and SCA11 are caused by specific gene mutations such as missense, inframe deletions, and frameshift insertions or deletions. SCA6 is caused by trinucleotide CAG repeat expansions encoding large uninterrupted glutamine tracts. SCA31 is caused by repeat expansions that fall outside of the protein-coding region of the disease gene. Currently, there are no specific gene mutations associated with SCA26 or SCA30, though there is a confirmed locus for each subtype. This disease is mainly diagnosed via genetic testing; however, differential diagnoses include pure cerebellar ataxia and non-cerebellar features in addition to ataxia. Although not fatal, ADCA Type III may cause dysphagia and falls, which reduce the quality of life of the patients and may in turn shorten the lifespan. The therapy for ADCA Type III is supportive and includes occupational and speech modalities. There is no cure for ADCA Type III, but a number of recent studies have highlighted novel therapies, which bring hope for future curative treatments. PMID:23331413

The role of Ag buffer layer in Fe islands growth on Ge (111) surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Tsu-Yi, E-mail: phtifu@phy.ntnu.edu.tw; Wu, Jia-Yuan; Jhou, Ming-Kuan

2015-05-07

Sub-monolayer iron atoms were deposited at room temperature on Ge (111)-c(2 × 8) substrates with and without Ag buffer layers. The behavior of Fe islands growth was investigated by using scanning tunneling microscope (STM) after different annealing temperatures. STM images show that iron atoms will cause defects and holes on substrates at room temperature. As the annealing temperature rises, iron atoms pull out germanium to form various kinds of alloyed islands. However, the silver layer can protect the Ag/Ge(111)-(√3×√3) reconstruction from forming defects. The phase diagram shows that ring, dot, and triangular defects were only found on Ge (111)-c(2 × 8) substrates. The kindsmore » of islands found in Fe/Ge system are similar to Fe/Ag/Ge system. It indicates that Ge atoms were pulled out to form islands at high annealing temperatures whether there was a Ag layer or not. But a few differences in big pyramidal or strip islands show that the silver layer affects the development of islands by changing the surface symmetry and diffusion coefficient. The structure characters of various islands are also discussed.« less

Imaging a Pyramid Interior by ERT-3D Methods, Preliminar Results at El Castillo Pyramid, Chichen Itza, Mexico

NASA Astrophysics Data System (ADS)

Chavez, R. E.; Tejero, A.; Cifuentes, G.; HernaNdez-Quintero, J. E.; Garcia-Serrano, A.

2016-12-01

The well known Pyramid El Castillo, located in the archaeological site of Chichen Itza, in the Yucatan Peninsula is the emblematic structure of this archaeological site and elected as one of the man-made world seven wonders. The archaeological team that restored this structure during the 1920's discovered a smaller pyramid inside this prehispanic body, which corresponded to an older Mayan period. The possibility of finding other constructive periods inside this edifice should be important to reconstruct the Mayan history. Previous geophysical studies carried out by us in 2014, employed novel Electrical Resistivity Tomography (ERT) arrays that surrounded the pyramids surface with flat electrodes to obtain a 3D image of the subsoil. At that time, a low resistivity body was found beneath the pyramid, which was associated to a sinkhole filled with sweet water. Employing the same technique, a series of flat electrodes were deployed on each body conforming the pyramid, a total of 10 bodies were covered, employing a different number of electrodes trying to keep the distance between each electrode constant ( 3 m). Each body was treated as a single observation cube, where the apparent resistivity data measured was later inverted. A precise topographic control for each electrode was realized and introduced in the inversion process. 45,000 observation points within the pyramid were obtained. Initially, each working cube corresponding to a given pyramid's body was inverted. A composition of each inversion was assembled to form the resistivity distribution within the pyramid using a smooth interpolation method. A high resistivity anomaly was found towards the northern portion of the model that could be associated to the main stairway of the inner pyramid. The cavity detected during the 2014 survey was observed as a low resistivity anomaly found at the pyramid's base. At the moment, we are assembling the full observed resistivity data as a single file to compute an integrated geophysical model that could be inverted. We expect to compute such final model soon.

Synthesis, antimicrobial, antioxidant and molecular docking studies of thiophene based macrocyclic Schiff base complexes

NASA Astrophysics Data System (ADS)

Rathi, Parveen; Singh, D. P.

2015-11-01

The macrocyclic complexes of pharmaceutical importance with trivalent transition metals have been synthesized by [1 + 1] condensation of succinyldihydrazide and thiophenedicarboxaldehyde, via template method, resulting in the formation of the complex [MLX] X2; where L is (C10H10N4O2S), a macrocyclic ligand, M = Cr (III) and Fe (III) and X = Cl-, CH3COO- or NO3- . These complexes have been characterized with the help of elemental analyses, molar conductance measurements, magnetic susceptibility measurements, ultraviolet, infrared, far infrared, electron spin resonance, mass spectral studies and powder x-ray diffraction analysis. On the basis of all these studies, mononuclear complexes having 1:2 electrolytic nature with a five coordinated square pyramidal geometry have been proposed. Powder diffraction XRD indicates the presence of triclinic crystal system with p bravais lattice for the representative complex. All the metal complexes have also been explored for their in vitro antimicrobial and antioxidant activities.

Synthesis and decomposition of a novel carboxylate precursor to indium oxide

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Andras, Maria T.; Duraj, Stan A.; Clark, Eric B.; Hehemann, David G.; Scheiman, Daniel A.; Fanwick, Phillip E.

1994-01-01

Reaction of metallic indium with benzoyl peroxide in 4-1 methylpyridine (4-Mepy) at 25 C produces an eight-coordinate mononuclear indium(III) benzoate, In(eta(sup 2)-O2CC6H5)3(4-Mepy)2 4H2O (I), in yields of up to 60 percent. The indium(III) benzoate was fully characterized by elemental analysis, spectroscopy, and X-ray crystallography; (I) exists in the crystalline state as discrete eight-coordinate molecules; the coordination sphere around the central indium atom is best described as pseudo-square pyramidal. Thermogravimetric analysis of (I) and X-ray diffraction powder studies on the resulting pyrolysate demonstrate that this new benzoate is an inorganic precursor to indium oxide. Decomposition of (I) occurs first by loss of 4-methylpyridine ligands (100 deg-200 deg C), then loss of benzoates with formation of In2O3 at 450 C. We discuss both use of carboxylates as precursors and our approach to their preparation.

Synthesis,and structural characterization of [(CH3(C5H4N))Ga(SCH2(CO)O)]-[(4-MepyH)]+, a novel Ga(III) five coordinate complex.

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Duraj, Stan A.; Fanwic, Phillp E.; Hepp, Aloysius F.; Martuch, Robert A.

2003-01-01

The synthesis and structural characterization of a novel ionic Ga(III) five coordinate complex [{CH3(C5H4N)}Ga(SCH2(CO)O)2]-[(4-MepyH)]+, (4-Mepy = CH3(C5H5N)) from the reaction between Ga2Cl4 with sodium mercapto-acetic acid in 4-methylpyridine is described. Under basic reaction conditions the mercapto ligand is found to behave as a 2e- bidentate ligand. Single crystal X-ray diffraction studies show the complex to have a distorted square pyramidal geometry with the [(-SCH2(CO)CO-)] ligands in a trans conformation. The compound crystallizes in the P2(sub 1)/c (No. 14) space group with a = 7.7413(6) A, b = 16.744(2) A, c = 14.459(2) A, V = 1987.1(6) A(sup 3), R(F) = 0.032 and R(sub w) = 0.038.

Cerebellar microfolia and other abnormalities of neuronal growth, migration, and lamination in the Pit1dw-J homozygote mutant mouse

NASA Technical Reports Server (NTRS)

Sekiguchi, M.; Abe, H.; Moriya, M.; Tanaka, O.; Nowakowski, R. S.

1998-01-01

The Snell dwarf mouse (Pit1dw-J homozygote) has a mutation in the Pit1 gene that prevents the normal formation of the anterior pituitary. In neonates and adults there is almost complete absence of growth hormone (GH), prolactin (PRL), thyroxin (T4), and thyroid-stimulating hormone (TSH). Since these hormones have been suggested to play a role in normal development of the central nervous system (CNS), we have investigated the effects of the Pit1dw-J mutation on the cerebellum and hippocampal formation. In the cerebellum, there were abnormalities of both foliation and lamination. The major foliation anomalies were 1) changes in the relative size of specific folia and also the proportional sizes of the anterior vs posterior cerebellum; and 2) the presence of between one and three microfolia per half cerebellum. The microfolia were all in the medial portion of the hemisphere in the caudal part of the cerebellum. Each microfolium was just rostral to a normal fissure and interposed between the fissure and a normal gyrus. Lamination abnormalities included an increase in the number of single ectopic granule cells in the molecular layer in both cerebellar vermis (86%) and hemisphere (40%) in comparison with the wild-type mouse. In the hippocampus of the Pit1dw-J homozygote mouse, the number of pyramidal cells was decreased, although the width of the pyramidal cell layer throughout areas CA1-CA3 appeared to be normal, but less densely populated than in the wild-type mouse. Moreover, the number of granule cells that form the granule cell layer was decreased from the wild-type mouse and some ectopic granule cells (occurring both as single cells and as small clusters) were observed in the innermost portion of the molecular layer. The abnormalities observed in the Pit1dw-J homozygote mouse seem to be caused by both direct and indirect effects of the deficiency of TSH (or T4), PRL, or GH rather than by a direct effect of the deletion of Pit1.

Lateral electrochemical etching of III-nitride materials for microfabrication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Jung

Conductivity-selective lateral etching of III-nitride materials is described. Methods and structures for making vertical cavity surface emitting lasers with distributed Bragg reflectors via electrochemical etching are described. Layer-selective, lateral electrochemical etching of multi-layer stacks is employed to form semiconductor/air DBR structures adjacent active multiple quantum well regions of the lasers. The electrochemical etching techniques are suitable for high-volume production of lasers and other III-nitride devices, such as lasers, HEMT transistors, power transistors, MEMs structures, and LEDs.

The force pyramid: a spatial analysis of force application during virtual reality brain tumor resection.

PubMed

Azarnoush, Hamed; Siar, Samaneh; Sawaya, Robin; Zhrani, Gmaan Al; Winkler-Schwartz, Alexander; Alotaibi, Fahad Eid; Bugdadi, Abdulgadir; Bajunaid, Khalid; Marwa, Ibrahim; Sabbagh, Abdulrahman Jafar; Del Maestro, Rolando F

2017-07-01

OBJECTIVE Virtual reality simulators allow development of novel methods to analyze neurosurgical performance. The concept of a force pyramid is introduced as a Tier 3 metric with the ability to provide visual and spatial analysis of 3D force application by any instrument used during simulated tumor resection. This study was designed to answer 3 questions: 1) Do study groups have distinct force pyramids? 2) Do handedness and ergonomics influence force pyramid structure? 3) Are force pyramids dependent on the visual and haptic characteristics of simulated tumors? METHODS Using a virtual reality simulator, NeuroVR (formerly NeuroTouch), ultrasonic aspirator force application was continually assessed during resection of simulated brain tumors by neurosurgeons, residents, and medical students. The participants performed simulated resections of 18 simulated brain tumors with different visual and haptic characteristics. The raw data, namely, coordinates of the instrument tip as well as contact force values, were collected by the simulator. To provide a visual and qualitative spatial analysis of forces, the authors created a graph, called a force pyramid, representing force sum along the z-coordinate for different xy coordinates of the tool tip. RESULTS Sixteen neurosurgeons, 15 residents, and 84 medical students participated in the study. Neurosurgeon, resident and medical student groups displayed easily distinguishable 3D "force pyramid fingerprints." Neurosurgeons had the lowest force pyramids, indicating application of the lowest forces, followed by resident and medical student groups. Handedness, ergonomics, and visual and haptic tumor characteristics resulted in distinct well-defined 3D force pyramid patterns. CONCLUSIONS Force pyramid fingerprints provide 3D spatial assessment displays of instrument force application during simulated tumor resection. Neurosurgeon force utilization and ergonomic data form a basis for understanding and modulating resident force application and improving patient safety during tumor resection.

A Rebuttal of NTL Institute's Learning Pyramid

ERIC Educational Resources Information Center

Letrud, Kare

2012-01-01

This article discusses the learning pyramid corroborated by National Training Laboratories Institute. It present and compliment historical and methodological critique against the learning pyramid, and call upon NTL Institute ought to retract their model.

The 2005 Food Guide Pyramid: an opportunity lost?

PubMed

Chiuve, Stephanie E; Willett, Walter C

2007-11-01

Dietary quality has a vital role in the prevention of chronic disease. In 2005, the US Department of Agriculture released a new food guide, MyPyramid, because the previous pyramid was in substantial discordance with current scientific evidence. The US Department of Agriculture pyramids are the most visible source of US nutrition policy and dietary guidance and it is, therefore, imperative they provide scientifically derived recommendations for a healthy diet. Unfortunately, MyPyramid strays from much of the evidence generated through years of research and, in our opinion, fails to provide the public with clear information about healthy food choices. In this Review, we discuss the policy and process behind the development of MyPyramid, assess the current evidence linking diet to chronic diseases, including cardiovascular disease, cancer and diabetes, and suggest potential alternatives for dietary recommendations.

Effect of varying durations of pyramid exposure - an indication towards a possibility of overexposure.

PubMed

Bhat, Surekha; Rao, Guruprasad; Murthy, K Dilip; Bhat, P Gopalakrishna

2009-10-01

Miniature replicas modeled after the Great Pyramid of Giza are believed to concentrate geoelectromagnetic energy within their cavities and hence act as antistressors in humans and animals. Although there are not many reports of adverse effects of 'overexposure' in the pyramid, subjects have claimed to feel uneasy after certain duration of staying in the pyramid. The present study was aimed to analyze the effects of prolonged pyramid exposure on plasma cortisol level, markers of oxidative damage and antioxidant defense in erythrocytes of adult female Wistar rats. Rats were divided into three groups, normal controls (NC, n=6) that were maintained under standard laboratory conditions in their home cages, pyramid exposed group-2 (PE-2, n=6) & pyramid exposed group-4 (PE-4, n=6) where the rats were housed under the pyramid for 6 hours/day for 2 weeks and 4 weeks respectively. Plasma cortisol and erythrocyte TBARS levels were significantly lower in both PE-2 and PE-4 rats and erythrocyte GSH levels and GSH-Px activity were significantly higher in them as compared to the NC rats. There was no significant difference in the results for these parameters between the PE-2 and PE-4 rats except for erythrocyte GSH-Px activity which was significantly more in the PE-2 rats than in the PE-4 rats. Although these results don't confirm any adverse effects of prolonged exposure in pyramids, they indicate a possibility of such adverse effects.

Challenges to rebuilding the US food pyramid.

PubMed

Kinney, John M

2005-01-01

Twelve years have passed since the US Department of Agriculture introduced the Food Guide Pyramid as a single visual expression of the major food groups and their relative amounts in a healthy diet. Unfortunately, no regular review has been conducted to incorporate new knowledge. Some feel that the pyramid format is too limited for modern use, while others wish it to continue with new information. It seems timely to review what features of the pyramid design have been useful over past years and how it can be improved with new concepts while maintaining ease of understanding by the average consumer. Examples are presented of adapting the pyramid to diets promoted by a special group or to support particular dietary beliefs, in contrast to the goal of seeking a single standardized format. Inherent limitations of the pyramid format are discussed. One proposal is discussed which seeks to redesign the pyramid into a modern educational tool presenting current concepts supported by recent studies and outcomes data. Popular beliefs about what is a healthy diet have perhaps never been as varied as now. This is partly due to sharply differing opinions about which highly publicized weight-loss diet is most effective. The educational benefits of the pyramid format need objective study in view of the inherent limitations of that configuration. Only when the specific visual advantages for the consumer are shown can a decision be made as to the benefit of major new efforts to construct a single modern pyramid.

Conductive atomic force microscopy studies on the transformation of GeSi quantum dots to quantum rings.

PubMed

Zhang, S L; Xue, F; Wu, R; Cui, J; Jiang, Z M; Yang, X J

2009-04-01

Conductive atomic force microscopy has been employed to study the topography and conductance distribution of individual GeSi quantum dots (QDs) and quantum rings (QRs) during the transformation from QDs to QRs by depositing an Si capping layer on QDs. The current distribution changes significantly with the topographic transformation during the Si capping process. Without the capping layer, the QDs are dome-shaped and the conductance is higher at the ring region between the center and boundary than that at the center. After capping with 0.32 nm Si, the shape of the QDs changes to pyramidal and the current is higher at both the center and the arris. When the Si capping layer increases to 2 nm, QRs are formed and the current of individual QRs is higher at the rim than that at the central hole. By comparing the composition distributions obtained by scanning Auger microscopy and atomic force microscopy combined with selective chemical etching, the origin of the current distribution change is discussed.

III-Nitride Digital Alloy: Electronics and Optoelectronics Properties of the InN/GaN Ultra-Short Period Superlattice Nanostructures.

PubMed

Sun, Wei; Tan, Chee-Keong; Tansu, Nelson

2017-07-27

The III-Nitride digital alloy (DA) is comprehensively studied as a short-period superlattice nanostructure consisting of ultra-thin III-Nitride epitaxial layers. By stacking the ultra-thin III-Nitride epitaxial layers periodically, these nanostructures are expected to have comparable optoelectronic properties as the conventional III-Nitride alloys. Here we carried out numerical studies on the InGaN DA showing the tunable optoelectronic properties of the III-Nitride DA. Our study shows that the energy gap of the InGaN DA can be tuned from ~0.63 eV up to ~2.4 eV, where the thicknesses and the thickness ratio of each GaN and InN ultra-thin binary layers within the DA structure are the key factors for tuning bandgap. Correspondingly, the absorption spectra of the InGaN DA yield broad wavelength tunability which is comparable to that of bulk InGaN ternary alloy. In addition, our investigation also reveals that the electron-hole wavefunction overlaps are remarkably large in the InGaN DA structure despite the existence of strain effect and build-in polarization field. Our findings point out the potential of III-Nitride DA as an artificially engineered nanostructure for optoelectronic device applications.

Entorhinal Cortical Ocean Cells Encode Specific Contexts and Drive Context-Specific Fear Memory

PubMed Central

Kitamura, Takashi; Sun, Chen; Martin, Jared; Kitch, Lacey J; Schnitzer, Mark J; Tonegawa, Susumu

2016-01-01

Summary Forming distinct representations and memories of multiple contexts and episodes is thought to be a crucial function of the hippocampal-entorhinal cortical network. The hippocampal dentate gyrus (DG) and CA3 are known to contribute to these functions but the role of the entorhinal cortex (EC) is poorly understood. Here, we show that Ocean cells, excitatory stellate neurons in the medial EC layer II projecting into DG and CA3, rapidly form a distinct representation of a novel context and drive context-specific activation of downstream CA3 cells as well as context-specific fear memory. In contrast, Island cells, excitatory pyramidal neurons in the medial EC layer II projecting into CA1, are indifferent to context-specific encoding or memory. On the other hand, Ocean cells are dispensable for temporal association learning, for which Island cells are crucial. Together, the two excitatory medial EC layer II inputs to the hippocampus have complementary roles in episodic memory. PMID:26402611

Circuit-specific intracortical hyperconnectivity in mice with deletion of the autism-associated Met receptor tyrosine kinase.

PubMed

Qiu, Shenfeng; Anderson, Charles T; Levitt, Pat; Shepherd, Gordon M G

2011-04-13

Local hyperconnectivity in the neocortex is a hypothesized pathophysiological state in autism spectrum disorder (ASD). MET, a receptor tyrosine kinase that regulates dendrite and spine morphogenesis, has been established as a risk gene for ASD. Here, we analyzed the synaptic circuit organization of identified pyramidal neurons in the anterior frontal cortex of mice with a dorsal pallium-derived, conditional knock-out (cKO) of Met. Synaptic mapping by glutamate uncaging identified layer 2/3 as the main source of local excitatory input to layer 5 projection neurons in controls. In both cKO and heterozygotes, this pathway was stronger by a factor of approximately 2. This increase was both sublayer and projection-class specific, restricted to corticostriatal neurons in upper layer 5B and not neighboring corticopontine neurons. Paired recordings in cKO slices demonstrated increased unitary connectivity. We propose that excitatory hyperconnectivity in specific neocortical microcircuits constitutes a physiological basis for Met-mediated ASD risk.

Adsorption and possible dissociation of glucose by the [BN fullerene-B6]- magnetic nanocomposite. In silico studies

NASA Astrophysics Data System (ADS)

Anota, E. Chigo; Villanueva, M. Salazar; Shakerzadeh, E.; Castro, M.

2018-02-01

The adsorption, activation and possible dissociation of the glucose molecule on the magnetic [BN fullerene-B6]- system is performed by means of density functional theory calculations. Three models of magnetic nanocomposites were inspected: i) pristine BN fullerene, BN fullerene functionalized with a magnetic B6 cluster which generates two structures: ii) pyramidal (P) and iii) triangular (T). Chemical interactions of glucose appear for all these cases; however, for the BNF:B6(T)—glucose system, the interaction generates an effect of dissociation on glucose, due to the magnetic effects, since it has high spin multiplicity. The latter nanocomposite shows electronic behavior like-conductor and like-semi-conductor for the P and T geometries, respectively. Intrinsic magnetism associated to values of 1.0 magneton bohr (µB) for the pyramidal and 5.0 µB for the triangular structure, high polarity, and low-chemical reactivity are found for these systems. These interesting properties make these functionalized fullerenes a good option for being used as nano-vehicles for drug delivery. These quantum descriptors remain invariant when the [BN]-fullerene and [BNF:B6 (P) or (T)]- nanocomposites are interacting with the glucose molecule. According to the determined adsorption energy, chemisorption regimes occur in both the phases: gas and aqueous medium.

The associations between blood lipids and the Food Guide Pyramid: findings from the Third National Health and Nutrition Examination Survey.

PubMed

Tande, Desiree L; Hotchkiss, Larry; Cotugna, Nancy

2004-04-01

Dietary recommendations are based on nutrients, foods, and food groups, but the relationship between the Food Guide Pyramid (FGP) food groups and serum lipids has not been studied. NHANES III data were obtained for US adults who met the following criteria: aged 20-59 years, reliable participant, and typical 24-h recall. We examined whether serum lipids (serum total cholesterol (STC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triacylglycerol) were related to FGP food group intake (dairy, fruit, grain, meat, and vegetable). A sample of 9111 participants qualified for this analysis. Fruit intakes were inversely related to STC, HDL-C, and LDL-C (P = 0.012, P = 0.001, and P = 0.014, respectively) and directly related to triacylglycerol levels (P = 0.003). Grain intake was inversely associated with both STC and HDL-C (P = 0.020 and P = 0.000). Dairy and meat intakes were directly related to LDL-C (P = 0.026 and P = 0.020). Food groups are related to serum lipids. Universal definitions for food groups are needed in research and nutrition education. Studying the relationships between food groups and serum lipids is important for future dietary recommendations related to serum lipids.

Detailed magnetic survey at Dahshour archeological sites Southwest Cairo, Egypt

NASA Astrophysics Data System (ADS)

Mekkawi, Mahmoud; Arafa-Hamed, Tarek; Abdellatif, Tareq

2013-06-01

Dahshour area has recently shown a great potential of archeological findings. This was remarkable from the latest discovery of the causeway and the mortuary temple of the Pyramid of Amenemhat III using geophysical data. The main objective of the present work is to locate the buried archeological remains in the area of Dahshour, Southwest Cairo using magnetic survey for shallow investigations. Land magnetic data is acquired using proton magnetometer (two sensors) with a sensor separation of 0.8 m; i.e. gradiometer survey. The study area is located nearby the two known pyramids of Dahshour. The field data is processed and analyzed using Oasis Montaj Geosoft™ software. The processed data is presented in order to delineate the hidden artifacts causing the magnetic anomalies. The results indicated a distribution of the buried archeological features within the study area. These archeological features are detected according to the magnetic contrast between the magnetic archeological sources (such as mud bricks, basalt and granite) and the surroundings; mainly sandy soil. The delineated archeological features at Dahshour are probably dated back to the old kingdom having a depth reach up to 3.0 m. Consequently it is highly recommended to carry out excavation to precisely classify them and high light their nature and value.

Activity of pyramidal I and II < c + a > slip in Mg alloys as revealed by texture development

NASA Astrophysics Data System (ADS)

Zecevic, Miroslav; Beyerlein, Irene J.; Knezevic, Marko

2018-02-01

Due to the geometry of the hexagonal close-packed (HCP) lattice, there are two types of pyramidal slip modes: { 10 1 bar 1 } 〈 11 2 bar 3 bar 〉 or type I and { 1 bar 1 bar 22 } 〈 11 2 bar 3 〉 or type II in HCP crystalline materials. Here we use crystal plasticity to examine the importance of crystallographic slip by pyramidal type I and type II on texture evolution. The study is applied to an Mg-4%Li alloy. An elastic-plastic polycrystal model is employed to elucidate the reorientation tendencies of these two slip modes in rolling of a textured polycrystal. Comparisons with experimental texture measurements indicate that both pyramidal I and II type slip were active during rolling deformation, with pyramidal I being the dominant mode. A single-slip-mode analysis is used to identify the orientations that prefer pyramidal I vs. II type slip when acting alone in a crystal. The analysis applies not only to Mg-4%Li, but identifies the key texture components in HCP crystals that would help distinguish the activity of pyramidal I from pyramidal II slip in rolling deformation.

Ion-implanted planar-buried-heterostructure diode laser

DOEpatents

Brennan, Thomas M.; Hammons, Burrell E.; Myers, David R.; Vawter, Gregory A.

1991-01-01

A Planar-Buried-Heterostructure, Graded-Index, Separate-Confinement-Heterostructure semiconductor diode laser 10 includes a single quantum well or multi-quantum well active stripe 12 disposed between a p-type compositionally graded Group III-V cladding layer 14 and an n-type compositionally graded Group III-V cladding layer 16. The laser 10 includes an ion implanted n-type region 28 within the p-type cladding layer 14 and further includes an ion implanted p-type region 26 within the n-type cladding layer 16. The ion implanted regions are disposed for defining a lateral extent of the active stripe.

Enlargement of Axo-Somatic Contacts Formed by GAD-Immunoreactive Axon Terminals onto Layer V Pyramidal Neurons in the Medial Prefrontal Cortex of Adolescent Female Mice Is Associated with Suppression of Food Restriction-Evoked Hyperactivity and Resilience to Activity-Based Anorexia.

PubMed

Chen, Yi-Wen; Wable, Gauri Satish; Chowdhury, Tara Gunkali; Aoki, Chiye

2016-06-01

Many, but not all, adolescent female mice that are exposed to a running wheel while food restricted (FR) become excessive wheel runners, choosing to run even during the hours of food availability, to the point of death. This phenomenon is called activity-based anorexia (ABA). We used electron microscopic immunocytochemistry to ask whether individual differences in ABA resilience may correlate with the lengths of axo-somatic contacts made by GABAergic axon terminals onto layer 5 pyramidal neurons (L5P) in the prefrontal cortex. Contact lengths were, on average, 40% greater for the ABA-induced mice, relative to controls. Correspondingly, the proportion of L5P perikaryal plasma membrane contacted by GABAergic terminals was 45% greater for the ABA mice. Contact lengths in the anterior cingulate cortex correlated negatively and strongly with the overall wheel activity after FR (R = -0.87, P < 0.01), whereas those in the prelimbic cortex correlated negatively with wheel running specifically during the hours of food availability of the FR days (R = -0.84, P < 0.05). These negative correlations support the idea that increases in the glutamic acid decarboxylase (GAD) terminal contact lengths onto L5P contribute toward ABA resilience through suppression of wheel running, a behavior that is intrinsically rewarding and helpful for foraging but maladaptive within a cage. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Cortical neuron activation induced by electromagnetic stimulation: a quantitative analysis via modelling and simulation.

PubMed

Wu, Tiecheng; Fan, Jie; Lee, Kim Seng; Li, Xiaoping

2016-02-01

Previous simulation works concerned with the mechanism of non-invasive neuromodulation has isolated many of the factors that can influence stimulation potency, but an inclusive account of the interplay between these factors on realistic neurons is still lacking. To give a comprehensive investigation on the stimulation-evoked neuronal activation, we developed a simulation scheme which incorporates highly detailed physiological and morphological properties of pyramidal cells. The model was implemented on a multitude of neurons; their thresholds and corresponding activation points with respect to various field directions and pulse waveforms were recorded. The results showed that the simulated thresholds had a minor anisotropy and reached minimum when the field direction was parallel to the dendritic-somatic axis; the layer 5 pyramidal cells always had lower thresholds but substantial variances were also observed within layers; reducing pulse length could magnify the threshold values as well as the variance; tortuosity and arborization of axonal segments could obstruct action potential initiation. The dependence of the initiation sites on both the orientation and the duration of the stimulus implies that the cellular excitability might represent the result of the competition between various firing-capable axonal components, each with a unique susceptibility determined by the local geometry. Moreover, the measurements obtained in simulation intimately resemble recordings in physiological and clinical studies, which seems to suggest that, with minimum simplification of the neuron model, the cable theory-based simulation approach can have sufficient verisimilitude to give quantitatively accurate evaluation of cell activities in response to the externally applied field.

Learning rules for spike timing-dependent plasticity depend on dendritic synapse location.

PubMed

Letzkus, Johannes J; Kampa, Björn M; Stuart, Greg J

2006-10-11

Previous studies focusing on the temporal rules governing changes in synaptic strength during spike timing-dependent synaptic plasticity (STDP) have paid little attention to the fact that synaptic inputs are distributed across complex dendritic trees. During STDP, propagation of action potentials (APs) back to the site of synaptic input is thought to trigger plasticity. However, in pyramidal neurons, backpropagation of single APs is decremental, whereas high-frequency bursts lead to generation of distal dendritic calcium spikes. This raises the question whether STDP learning rules depend on synapse location and firing mode. Here, we investigate this issue at synapses between layer 2/3 and layer 5 pyramidal neurons in somatosensory cortex. We find that low-frequency pairing of single APs at positive times leads to a distance-dependent shift to long-term depression (LTD) at distal inputs. At proximal sites, this LTD could be converted to long-term potentiation (LTP) by dendritic depolarizations suprathreshold for BAC-firing or by high-frequency AP bursts. During AP bursts, we observed a progressive, distance-dependent shift in the timing requirements for induction of LTP and LTD, such that distal synapses display novel timing rules: they potentiate when inputs are activated after burst onset (negative timing) but depress when activated before burst onset (positive timing). These findings could be explained by distance-dependent differences in the underlying dendritic voltage waveforms driving NMDA receptor activation during STDP induction. Our results suggest that synapse location within the dendritic tree is a crucial determinant of STDP, and that synapses undergo plasticity according to local rather than global learning rules.

Cascaded K-means convolutional feature learner and its application to face recognition

NASA Astrophysics Data System (ADS)

Zhou, Daoxiang; Yang, Dan; Zhang, Xiaohong; Huang, Sheng; Feng, Shu

2017-09-01

Currently, considerable efforts have been devoted to devise image representation. However, handcrafted methods need strong domain knowledge and show low generalization ability, and conventional feature learning methods require enormous training data and rich parameters tuning experience. A lightened feature learner is presented to solve these problems with application to face recognition, which shares similar topology architecture as a convolutional neural network. Our model is divided into three components: cascaded convolution filters bank learning layer, nonlinear processing layer, and feature pooling layer. Specifically, in the filters learning layer, we use K-means to learn convolution filters. Features are extracted via convoluting images with the learned filters. Afterward, in the nonlinear processing layer, hyperbolic tangent is employed to capture the nonlinear feature. In the feature pooling layer, to remove the redundancy information and incorporate the spatial layout, we exploit multilevel spatial pyramid second-order pooling technique to pool the features in subregions and concatenate them together as the final representation. Extensive experiments on four representative datasets demonstrate the effectiveness and robustness of our model to various variations, yielding competitive recognition results on extended Yale B and FERET. In addition, our method achieves the best identification performance on AR and labeled faces in the wild datasets among the comparative methods.

Disposable gold coated pyramidal SERS sensor on the plastic platform.

PubMed

Oo, S Z; Siitonen, S; Kontturi, V; Eustace, D A; Charlton, M D B

2016-01-11

In this paper we investigate suitability of arrays of gold coated pyramids for surface-enhanced Raman scattering (SERS) sensing applications. Pyramidarrays composed of 1000 nm pit size with 1250 nm pitch lengthwerereplicated on a plastic substrate by roll-to-roll (R2R) ultraviolet (UV) embossing. The level of SERS enhancement, and qualitative performance provided by the new substrate is investigated by comparing Raman spectrum of benzenethiol (BTh) test molecules to the benchmark Klarite SERS substrate which comprises inverted pyramid arrays(1500 nm pit size with 2000 nm pitch length) fabricated on a silicon substrate. The new substrate is found to provide upto 11 times increase in signal in comparison to the inverted pyramid (IV-pyramid) arrays fabricated on an identical plastic substrate. Numerical simulation and experimental evidence suggest that strongly confined electromagnetic fields close to the base of the pyramids, are mainly responsible for the Raman enhancement factor, instead of the fields localized around the tip. Unusually strong plasmon fields are projected upto 200nm from the sidewalls at the base of the pyramid increasing the cross sectional sensing volume.

Pyramidal Cells in Prefrontal Cortex of Primates: Marked Differences in Neuronal Structure Among Species

PubMed Central

Elston, Guy N.; Benavides-Piccione, Ruth; Elston, Alejandra; Manger, Paul R.; DeFelipe, Javier

2010-01-01

The most ubiquitous neuron in the cerebral cortex, the pyramidal cell, is characterized by markedly different dendritic structure among different cortical areas. The complex pyramidal cell phenotype in granular prefrontal cortex (gPFC) of higher primates endows specific biophysical properties and patterns of connectivity, which differ from those in other cortical regions. However, within the gPFC, data have been sampled from only a select few cortical areas. The gPFC of species such as human and macaque monkey includes more than 10 cortical areas. It remains unknown as to what degree pyramidal cell structure may vary among these cortical areas. Here we undertook a survey of pyramidal cells in the dorsolateral, medial, and orbital gPFC of cercopithecid primates. We found marked heterogeneity in pyramidal cell structure within and between these regions. Moreover, trends for gradients in neuronal complexity varied among species. As the structure of neurons determines their computational abilities, memory storage capacity and connectivity, we propose that these specializations in the pyramidal cell phenotype are an important determinant of species-specific executive cortical functions in primates. PMID:21347276

Method of removing oxidized contaminants from water

DOEpatents

Amonette, James E.; Fruchter, Jonathan S.; Gorby, Yuri A.; Cole, Charles R.; Cantrell, Kirk J.; Kaplan, Daniel I.

1998-01-01

The present invention is a method for removing oxidized contaminant(s) from water. More specifically, the invention has the steps of contacting water containing the oxidized contaminant(s) with a layered aluminosilicate having Fe(II). The aluminosilicate may contain naturally occurring Fe(II), or the Fe(II) may be produced by reducing Fe(III) that is initially present. Reduction may be either by exposure to a chemical or biological reductant. Contacting the water containing oxidized contaminant(s) may be by (1) injection of Fe(II)-containing layered aluminosilicate, via a well, into a saturated zone where it is likely to intercept the contaminated water; (2) injection of contaminated water into a vessel containing the Fe(II)-bearing layered aluminosilicate; and (3) first reducing Fe(III) in the layered aluminosilicate to Fe(II) by injection of a biological or chemical reductant, into an aquifer or vessel having sufficient Fe(III)-bearing aluminosilicate to produce the necessary Fe(II).

Method of removing oxidized contaminants from water

DOEpatents

Amonette, J.E.; Fruchter, J.S.; Gorby, Y.A.; Cole, C.R.; Cantrell, K.J.; Kaplan, D.I.

1998-07-21

The present invention is a method for removing oxidized contaminant(s) from water. More specifically, the invention has the steps of contacting water containing the oxidized contaminant(s) with a layered aluminosilicate having Fe(II). The aluminosilicate may contain naturally occurring Fe(II), or the Fe(II) may be produced by reducing Fe(III) that is initially present. Reduction may be either by exposure to a chemical or biological reductant. Contacting the water containing oxidized contaminant(s) may be by (1) injection of Fe(II)-containing layered aluminosilicate, via a well, into a saturated zone where it is likely to intercept the contaminated water; (2) injection of contaminated water into a vessel containing the Fe(II)-bearing layered aluminosilicate; and (3) first reducing Fe(III) in the layered aluminosilicate to Fe(II) by injection of a biological or chemical reductant, into an aquifer or vessel having sufficient Fe(III)-bearing aluminosilicate to produce the necessary Fe(II). 8 figs.

Two-dimensional 3d-4f heterometallic coordination polymers: syntheses, crystal structures, and magnetic properties of six new Co(II)-Ln(III) compounds.

PubMed

Díaz-Gallifa, Pau; Fabelo, Oscar; Pasán, Jorge; Cañadillas-Delgado, Laura; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

2014-06-16

Six new heterometallic cobalt(II)-lanthanide(III) complexes of formulas [Ln(bta)(H2O)2]2[Co(H2O)6]·10H2O [Ln = Nd(III) (1) and Eu(III) (2)] and [Ln2Co(bta)2(H2O)8]n·6nH2O [Ln = Eu(III) (3), Sm(III) (4), Gd(III) (5), and Tb(III) (6)] (H4bta = 1,2,4,5-benzenetretracaboxylic acid) have been synthesized and characterized via single-crystal X-ray diffraction. 1 and 2 are isostructural compounds with a structure composed of anionic layers of [Ln(bta)(H2O)2]n(n-) sandwiching mononuclear [Co(H2O)6](2+) cations plus crystallization water molecules, which are interlinked by electrostatic forces and hydrogen bonds, leading to a supramolecular three-dimensional network. 3-6 are also isostructural compounds, and their structure consists of neutral layers of formula [Ln2Co(bta)2(H2O)8]n and crystallization water molecules, which are connected through hydrogen bonds to afford a supramolecular three-dimensional network. Heterometallic chains formed by the regular alternation of two nine-coordinate lanthanide(III) polyhedra [Ln(III)O9] and one compressed cobalt(II) octahedron [Co(II)O6] along the crystallographic c-axis are cross-linked by bta ligands within each layer of 3-6. Magnetic susceptibility measurements on polycrystalline samples for 3-6 have been carried out in the temperature range of 2.0-300 K. The magnetic behavior of these types of Ln(III)-Co(II) complexes, which have been modeled by using matrix dagonalization techniques, reveals the lack of magnetic coupling for 3 and 4, and the occurrence of weak antiferromagnetic interactions within the Gd(III)-Gd(III) (5) and Tb(III)-Tb(III) (6) dinuclear units through the exchange pathway provided by the double oxo(carboxylate) and double syn-syn carboxylate bridges.

Recurrent apnea induces neuronal apoptosis in the guinea pig forebrain.

PubMed

Zhang, Jian-Hua; Fung, Simon J; Xi, Mingchu; Sampogna, Sharon; Chase, Michael H

2009-04-01

Obstructive sleep apnea (OSA) and sleep-disordered breathing (SDB) can result in impaired cognition and mental acuity, and the generation of mood disorders, including depression. However, the mechanisms of neuronal damage for these complications have not been elucidated. Accordingly, using immunohistochemical technique with monoclonal antibody against single-stranded DNA, we examined the morphological effects of chronic recurrent apnea on neurons in the hippocampus and related forebrain sites in guinea pigs. Our results show that a large number of neurons labeled by anti-ssDNA antibody were present in the cingulate, insular and frontal cortices, the hippocampus and the amygdala in conjunction with periods of recurrent apnea. However, no labeling was observed in comparable regions of the brain in control guinea pigs. In the cortices of experimental animals, labeled neurons were detected mainly in the superficial layers (II-III) in the frontal, insular and cingulate cortex. In the hippocampus, most labeled neurons were located in the CA1 region, in which most of stained neurons were observed in strata pyramidal, while only a few positive neurons were located in the strata radiatum and the strata oriens. In addition, a large number of labeled neurons were also detected in the central nucleus of amygdala in the guinea pigs underwent recurrent periods of apnea. The present data indicate that recurrent apnea results in cell death in the hippocampus and related forebrain regions via mechanisms of apoptosis, which may represent the basis for the clinical complications of obstructive sleep apnea and sleep-disordered breathing.

Models and simulation of 3D neuronal dendritic trees using Bayesian networks.

PubMed

López-Cruz, Pedro L; Bielza, Concha; Larrañaga, Pedro; Benavides-Piccione, Ruth; DeFelipe, Javier

2011-12-01

Neuron morphology is crucial for neuronal connectivity and brain information processing. Computational models are important tools for studying dendritic morphology and its role in brain function. We applied a class of probabilistic graphical models called Bayesian networks to generate virtual dendrites from layer III pyramidal neurons from three different regions of the neocortex of the mouse. A set of 41 morphological variables were measured from the 3D reconstructions of real dendrites and their probability distributions used in a machine learning algorithm to induce the model from the data. A simulation algorithm is also proposed to obtain new dendrites by sampling values from Bayesian networks. The main advantage of this approach is that it takes into account and automatically locates the relationships between variables in the data instead of using predefined dependencies. Therefore, the methodology can be applied to any neuronal class while at the same time exploiting class-specific properties. Also, a Bayesian network was defined for each part of the dendrite, allowing the relationships to change in the different sections and to model heterogeneous developmental factors or spatial influences. Several univariate statistical tests and a novel multivariate test based on Kullback-Leibler divergence estimation confirmed that virtual dendrites were similar to real ones. The analyses of the models showed relationships that conform to current neuroanatomical knowledge and support model correctness. At the same time, studying the relationships in the models can help to identify new interactions between variables related to dendritic morphology.

Progressive brain damage, synaptic reorganization and NMDA activation in a model of epileptogenic cortical dysplasia.

PubMed

Colciaghi, Francesca; Finardi, Adele; Nobili, Paola; Locatelli, Denise; Spigolon, Giada; Battaglia, Giorgio Stefano

2014-01-01

Whether severe epilepsy could be a progressive disorder remains as yet unresolved. We previously demonstrated in a rat model of acquired focal cortical dysplasia, the methylazoxymethanol/pilocarpine - MAM/pilocarpine - rats, that the occurrence of status epilepticus (SE) and subsequent seizures fostered a pathologic process capable of modifying the morphology of cortical pyramidal neurons and NMDA receptor expression/localization. We have here extended our analysis by evaluating neocortical and hippocampal changes in MAM/pilocarpine rats at different epilepsy stages, from few days after onset up to six months of chronic epilepsy. Our findings indicate that the process triggered by SE and subsequent seizures in the malformed brain i) is steadily progressive, deeply altering neocortical and hippocampal morphology, with atrophy of neocortex and CA regions and progressive increase of granule cell layer dispersion; ii) changes dramatically the fine morphology of neurons in neocortex and hippocampus, by increasing cell size and decreasing both dendrite arborization and spine density; iii) induces reorganization of glutamatergic and GABAergic networks in both neocortex and hippocampus, favoring excitatory vs inhibitory input; iv) activates NMDA regulatory subunits. Taken together, our data indicate that, at least in experimental models of brain malformations, severe seizure activity, i.e., SE plus recurrent seizures, may lead to a widespread, steadily progressive architectural, neuronal and synaptic reorganization in the brain. They also suggest the mechanistic relevance of glutamate/NMDA hyper-activation in the seizure-related brain pathologic plasticity.

Stress evolution of GaN/AlN heterostructure grown on 6H-SiC substrate by plasma assisted molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Agrawal, M.; Ravikiran, L.; Dharmarasu, N.; Radhakrishnan, K.; Karthikeyan, G. S.; Zheng, Y.

2017-01-01

The stress evolution of GaN/AlN heterostructure grown on 6H-SiC substrate by plasma assisted molecular beam epitaxy (PA-MBE) has been studied. AlN nucleation layer and GaN layer were grown as a function of III/V ratio. GaN/AlN structure is found to form buried cracks when AlN is grown in the intermediate growth regime(III/V˜1)and GaN is grown under N-rich growth regime (III/V<1). The III/V ratio determines the growth mode of the layers that influences the lattice mismatch at the GaN/AlN interface. The lattice mismatch induced interfacial stress at the GaN/AlN interface relaxes by the formation of buried cracks in the structure. Additionally, the stress also relaxes by misorienting the AlN resulting in two misorientations with different tilts. Crack-free layers were obtained when AlN and GaN were grown in the N-rich growth regime (III/V<1) and metal rich growth regime (III/V≥1), respectively. AlGaN/GaN high electron mobility transistor (HEMT) heterostructure was demonstrated on 2-inch SiC that showed good two dimensional electron gas (2DEG) properties with a sheet resistance of 480 Ω/sq, mobility of 1280 cm2/V.s and sheet carrier density of 1×1013 cm-2.

Cu sbnd Al sbnd Fe layered double hydroxides with CO32- and anionic surfactants with different alkyl chains in the interlayer

NASA Astrophysics Data System (ADS)

Trujillano, Raquel; Holgado, María Jesús; González, José Luis; Rives, Vicente

2005-08-01

Layered double hydroxides (LDHs), with the hydrotalcite-like structure containing Cu(II), Al(III) and Fe(III) in the layers, and different alkyl sulfonates in the interlayer, have been prepared and characterized by powder X-ray diffraction, FT-IR spectroscopy, differential thermal analysis and thermogravimetric analysis. Pure crystalline phases have been obtained in all cases. Upon heating, combustion of the organic chain takes place at lower temperature than the corresponding sodium salts.

A Managerial Approach to NASA’s Cultural Changes: Open System Model

DTIC Science & Technology

2007-12-01

in both societies was different, even though both resemble a similar pyramid shape. For the Egyptians , pyramids were tombs , and for the Mayans...to understand, Schein (2004) points out they may be difficult to decipher. An example is Egyptian and Mayan pyramids. The meaning of the structures...pyramids were both tombs and temples. Therefore, care must be taken deriving meaning from artifacts, especially in different societies (Schein, 2004

Light extraction efficiency of GaN-based LED with pyramid texture by using ray path analysis.

PubMed

Pan, Jui-Wen; Wang, Chia-Shen

2012-09-10

We study three different gallium-nitride (GaN) based light emitting diode (LED) cases based on the different locations of the pyramid textures. In case 1, the pyramid texture is located on the sapphire top surface, in case 2, the pyramid texture is locate on the P-GaN top surface, while in case 3, the pyramid texture is located on both the sapphire and P-GaN top surfaces. We study the relationship between the light extraction efficiency (LEE) and angle of slant of the pyramid texture. The optimization of total LEE was highest for case 3 among the three cases. Moreover, the seven escape paths along which most of the escaped photon flux propagated were selected in a simulation of the LEDs. The seven escape paths were used to estimate the slant angle for the optimization of LEE and to precisely analyze the photon escape path.

The architectonic encoding of the minor lunar standstills in the horizon of the Giza pyramids.

NASA Astrophysics Data System (ADS)

Hossam, M. K. Aboulfotouh

The paper is an attempt to show the architectonic method of the ancient Egyptian designers for encoding the horizontal-projections of the moon's declinations during two events of the minor lunar standstills, in the design of the site-plan of the horizon of the Giza pyramids, using the methods of descriptive geometry. It shows that the distance of the eastern side of the second Giza pyramid from the north-south axis of the great pyramid encodes a projection of a lunar declination, when earth's obliquity-angle was ~24.10°. Besides, it shows that the angle of inclination of the causeway of the second Giza pyramid, of ~13.54° south of the cardinal east, encodes the projection of another lunar declination when earth's obliquity-angle reaches ~22.986°. In addition, it shows the encoded coordinate system in the site-plan of the horizon of the Giza pyramids.

A two-dimensional hydrogen-bonded water layer in the structure of a cobalt(III) cubane complex.

PubMed

Qi, Ji; Zhai, Xiang-Sheng; Zhu, Hong-Lin; Lin, Jian-Li

2014-02-01

A tetranuclear Co(III) oxide complex with cubane topology, tetrakis(2,2'-bipyridine-κ(2)N,N')di-μ2-carbonato-κ(4)O:O'-tetra-μ3-oxido-tetracobalt(III) pentadecahydrate, [Co4(CO3)2O4(C10H8N2)4]·15H2O, with an unbounded hydrogen-bonded water layer, has been synthesized by reaction of CoCO3 and 2,2'-bipyridine. The solvent water molecules form a hydrogen-bonded net with tetrameric and pentameric water clusters as subunits. The Co4O4 cubane-like cores are sandwiched between the water layers, which are further stacked into a three-dimensional metallo-supramolecular network.

Floating Oil-Spill Containment Device

NASA Technical Reports Server (NTRS)

Jones, Jack A.

2012-01-01

Previous oil containment booms have an open top that allows natural gas to escape, and have significant oil leakage due to wave action. Also, a subsea pyramid oil trap exists, but cannot move relative to moving oil plumes from deepsea oil leaks. The solution is to have large, moveable oil traps. One version floats on the sea surface and has a flexible tarp cover and a lower weighted skirt to completely entrap the floating oil and natural gas. The device must have at least three sides with boats pulling at each apex, and sonar or other system to track the slowly moving oil plume, so that the boats can properly locate the booms. The oil trap device must also have a means for removal of the oil and the natural gas. A second design version has a flexible pyramid cover that is attached by lines to ballast on the ocean floor. This is similar to fixed, metal pyramid oil capture devices in the Santa Barbara Channel off the coast of California. The ballast lines for the improved design, however, would have winches that can move the pyramid to always be located above the oil and gas plume. A third design is a combination of the first two. It uses a submerged pyramid to trap oil, but has no anchor and uses boats to locate the trap. It has ballast weights located along the bottom of the tarp and/or at the corners of the trap. The improved floating oil-spill containment device has a large floating boom and weighted skirt surrounding the oil and gas entrapment area. The device is triangular (or more than three sides) and has a flexible tarp cover with a raised gas vent area. Boats pull on the apex of the triangles to maintain tension and to allow the device to move to optimum locations to trap oil and gas. The gas is retrieved from a higher buoyant part of the tarp, and oil is retrieved from the floating oil layer contained in the device. These devices can be operated in relatively severe weather, since waves will break over the devices without causing oil leaking. Also, natural gas is entrapped and can be retrieved. All designs can use sonar to locate the moving oil plume, and then be relocated by using boats or winches to move the oil trapping devices. These devices can be constructed of treated, non-permeable DuPont Kevlar cloth (or similar material).

NR2A-Containing NMDARs in the Prefrontal Cortex Are Required for Working Memory and Associated with Age-Related Cognitive Decline.

PubMed

McQuail, Joseph A; Beas, B Sofia; Kelly, Kyle B; Simpson, Kailey L; Frazier, Charles J; Setlow, Barry; Bizon, Jennifer L

2016-12-14

Working memory, the ability to temporarily maintain representational knowledge, is a foundational cognitive process that can become compromised in aging and neuropsychiatric disease. NMDA receptor (NMDAR) activation in prefrontal cortex (PFC) is necessary for the pyramidal neuron activity believed to enable working memory; however, the distinct biophysical properties and localization of NMDARs containing NR2A and NR2B subunits suggest unique roles for NMDAR subtypes in PFC neural activity and working memory. Experiments herein show that working memory depends on NR2A- but not NR2B-NMDARs in PFC of rats and that NR2A-NMDARs mediate the majority of evoked NMDAR currents on layer 2/3 PFC pyramidal neurons. Moreover, attenuated expression of the NR2A but not the NR2B subunit in PFC associates with naturally occurring working memory impairment in aged rats. Finally, NMDAR currents and working memory are enhanced in aged rats by promoting activation of the NR2A-enriched synaptic pool of PFC NMDARs. These results implicate NR2A-NMDARs in normal working memory and suggest novel treatment strategies for improving working memory in cognitive disorders. Working memory, the ability to hold information "in mind," requires persistent activity of pyramidal neurons in prefrontal cortex (PFC) mediated by NMDA receptor (NMDAR) activation. NMDAR loss in PFC may account for working memory impairments in aging and psychiatric disease. Our studies demonstrate that NMDARs containing the NR2A subunit, but not the NR2B subunit, are required for working memory and that loss of NR2A predicts severity of age-related working memory impairment. The importance of NR2A to working memory is likely due its abundant contribution to pyramidal neuron activity and location at synaptic sites in PFC. This information is useful in designing new therapies to treat working memory impairments by enhancing the function of NR2A-containing NMDARs. Copyright © 2016 the authors 0270-6474/16/3612537-12$15.00/0.

Neuronal Migration Dynamics in the Developing Ferret Cortex.

PubMed

Gertz, Caitlyn C; Kriegstein, Arnold R

2015-10-21

During mammalian neocortical development, newborn excitatory and inhibitory neurons must migrate over long distances to reach their final positions within the cortical plate. In the lissencephalic rodent brain, pyramidal neurons are born in the ventricular and subventricular zones of the pallium and migrate along radial glia fibers to reach the appropriate cortical layer. Although much less is known about neuronal migration in species with a gyrencephalic cortex, retroviral studies in the ferret and primate suggest that, unlike the rodent, pyramidal neurons do not follow strict radial pathways and instead can disperse horizontally. However, the means by which pyramidal neurons laterally disperse remain unknown. In this study, we identified a viral labeling technique for visualizing neuronal migration in the ferret, a gyrencephalic carnivore, and found that migration was predominantly radial at early postnatal ages. In contrast, neurons displayed more tortuous migration routes with a decreased frequency of cortical plate-directed migration at later stages of neurogenesis concomitant with the start of brain folding. This was accompanied by neurons migrating sequentially along several different radial glial fibers, suggesting a mode by which pyramidal neurons may laterally disperse in a folded cortex. These findings provide insight into the migratory behavior of neurons in gyrencephalic species and provide a framework for using nonrodent model systems for studying neuronal migration disorders. Elucidating neuronal migration dynamics in the gyrencephalic, or folded, cortex is important for understanding neurodevelopmental disorders. Similar to the rodent, we found that neuronal migration was predominantly radial at early postnatal ages in the gyrencephalic ferret cortex. Interestingly, ferret neurons displayed more tortuous migration routes and a decreased frequency of radial migration at later ages coincident with the start of cortical folding. We found that ferret neurons use several different radial glial fibers as migratory guides, including those belonging to the recently described outer radial glia, suggesting a mechanism by which ferret neurons disperse laterally. It is likely that excitatory neurons horizontally disperse in other gyrencephalic mammals, including the primate, suggesting an important modification to the current model deduced primarily from the rodent. Copyright © 2015 the authors 0270-6474/15/3514307-09$15.00/0.

Discovery of a big void in Khufu's Pyramid by observation of cosmic-ray muons.

PubMed

Morishima, Kunihiro; Kuno, Mitsuaki; Nishio, Akira; Kitagawa, Nobuko; Manabe, Yuta; Moto, Masaki; Takasaki, Fumihiko; Fujii, Hirofumi; Satoh, Kotaro; Kodama, Hideyo; Hayashi, Kohei; Odaka, Shigeru; Procureur, Sébastien; Attié, David; Bouteille, Simon; Calvet, Denis; Filosa, Christopher; Magnier, Patrick; Mandjavidze, Irakli; Riallot, Marc; Marini, Benoit; Gable, Pierre; Date, Yoshikatsu; Sugiura, Makiko; Elshayeb, Yasser; Elnady, Tamer; Ezzy, Mustapha; Guerriero, Emmanuel; Steiger, Vincent; Serikoff, Nicolas; Mouret, Jean-Baptiste; Charlès, Bernard; Helal, Hany; Tayoubi, Mehdi

2017-12-21

The Great Pyramid, or Khufu's Pyramid, was built on the Giza plateau in Egypt during the fourth dynasty by the pharaoh Khufu (Cheops), who reigned from 2509 bc to 2483 bc. Despite being one of the oldest and largest monuments on Earth, there is no consensus about how it was built. To understand its internal structure better, we imaged the pyramid using muons, which are by-products of cosmic rays that are only partially absorbed by stone. The resulting cosmic-ray muon radiography allows us to visualize the known and any unknown voids in the pyramid in a non-invasive way. Here we report the discovery of a large void (with a cross-section similar to that of the Grand Gallery and a minimum length of 30 metres) situated above the Grand Gallery. This constitutes the first major inner structure found in the Great Pyramid since the nineteenth century. The void, named ScanPyramids' Big Void, was first observed with nuclear emulsion films installed in the Queen's chamber, then confirmed with scintillator hodoscopes set up in the same chamber and finally re-confirmed with gas detectors outside the pyramid. This large void has therefore been detected with high confidence by three different muon detection technologies and three independent analyses. These results constitute a breakthrough for the understanding of the internal structure of Khufu's Pyramid. Although there is currently no information about the intended purpose of this void, these findings show how modern particle physics can shed new light on the world's archaeological heritage.

The Neocortex of Indian River Dolphins (Genus Platanista): Comparative, Qualitative and Quantitative Analysis.

PubMed

Knopf, Julian P; Hof, Patrick R; Oelschläger, Helmut H A

2016-01-01

We investigated the morphology of four primary neocortical projection areas (somatomotor, somatosensory, auditory, visual) qualitatively and quantitatively in the Indian river dolphins (Platanista gangetica gangetica, P. gangetica minor) with histological and stereological methods. For comparison, we included brains of other toothed whale species. Design-based stereology was applied to the primary neocortical areas (M1, S1, A1, V1) of the Indian river dolphins and compared to those of the bottlenose dolphin with respect to layers III and V. These neocortical fields were identified using existing electrophysiological and morphological data from marine dolphins as to their topography and histological structure, including the characteristics of the neuron populations concerned. In contrast to other toothed whales, the visual area (V1) of the 'blind' river dolphins seems to be rather small. M1 is displaced laterally and the auditory area (A1) is larger than in marine species with respect to total brain size. The layering is similar in the cortices of all the toothed whale brains investigated; a layer IV could not be identified. Cell density in layer III is always higher than in layer V. The maximal neuron density in P. gangetica gangetica is found in layer III of A1, followed by layers III in V1, S1, and M1. The cell density in layer V is at a similar level in all primary areas. There are, however, some differences in neuron density between the two subspecies of Indian river dolphins. Taken as a whole, it appears that the neocortex of platanistids exhibits a considerable expansion of the auditory field. Even more than other toothed whales, they seem to depend on their biosonar abilities for navigation, hunting, and communication in their riverine habitat. © 2016 S. Karger AG, Basel.

Monolithic in-based III-V compound semiconductor focal plane array cell with single stage CCD output

NASA Technical Reports Server (NTRS)

Fossum, Eric R. (Inventor); Cunningham, Thomas J. (Inventor); Krabach, Timothy N. (Inventor); Staller, Craig O. (Inventor)

1994-01-01

A monolithic semiconductor imager includes an indium-based III-V compound semiconductor monolithic active layer of a first conductivity type, an array of plural focal plane cells on the active layer, each of the focal plane cells including a photogate over a top surface of the active layer, a readout circuit dedicated to the focal plane cell including plural transistors formed monolithically with the monolithic active layer and a single-stage charge coupled device formed monolithically with the active layer between the photogate and the readout circuit for transferring photo-generated charge accumulated beneath the photogate during an integration period to the readout circuit. The photogate includes thin epitaxial semiconductor layer of a second conductivity type overlying the active layer and an aperture electrode overlying a peripheral portion of the thin epitaxial semiconductor layer, the aperture electrode being connectable to a photogate bias voltage.

Rebuilding the Food Pyramid.

ERIC Educational Resources Information Center

Willet, Walter C.; Stampfer, Meir J.

2003-01-01

Discusses the old food guide pyramid released in 1992 by the U.S. Department of Agriculture. Contradicts the message that fat is bad, which was presented to the public by nutritionists, and the effects of plant oils on cholesterol. Introduces a new food pyramid. (YDS)

Fate of chromium in soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prokisch, J.; Gyori, Z.; Kovacs, B.

The chromium cycle in soil was studied with speciation of chromium. The aim was to look for the possibilities the mobilization of chromium(III) and to measure the rate of chromate reduction in nature and pot and field experiments in Hungarian soils. The authors developed a sensitive and simple method for chromium speciation with a microcolumn connected an inductively coupled plasma atomic emission spectrometer. Detection limits are convenient to measure chromium forms in a 0.01 M CaCl{sub 2} extract of a contaminated soil, but it is not enough to measure that of the uncontaminated soils. CR(VI) as chromate anion is notmore » adsorbed on pH dependent temporary charges of clays but in strongly acidic soil. Therefore CR(VI) can be leached out easily from the top layer of soil and can be transported into the ground water. Chromate ion can be reduced to CR(III) by organic matter of soil in acidic medium. CR(VI) is more stable at higher pH and lower humus content. Thus the reduction much quicker in the upper, weakly acidic top layer. CR(VI) oxidizes the organic matter of soil. The rate of this reaction depends on pH values, the humus content of the soil and temperature. CR(III) leaching in different uncontaminated soils was studied too. There are 3 pathways of mobilization of Cr(III). When pH decreases in soil the CR(III) becomes more soluble, similarly to the aluminium(III) ion. When the soil contains large quantity of water soluble organic ligands, Cr makes complexes with them and complexes formed can be leached out from the top layer. The third possibility is the oxidation of CR(III) to Cr(VI). It could happen on surface of manganese dioxide in the well-aired top layer.« less

Improving socio-emotional health for pupils in early secondary education with Pyramid: A school-based, early intervention model.

PubMed

Jayman, Michelle; Ohl, Maddie; Hughes, Bronach; Fox, Pauline

2018-05-01

Policymakers are focusing increased attention on the role of schools to promote and support children's mental health, and evidence-based models of good practice are in demand. Pyramid Club is a school-based, socio-emotional intervention, demonstrably effective with primary-aged pupils. This study extends previous Pyramid Club evaluations by examining effectiveness with pupils in early secondary education; service users' perceptions and experiences were investigated to increase understanding of Pyramid's impact, thus supporting enhanced practice. Participants (n = 126) comprised selected pupils, aged 11-14 (52 males; 74 females), who completed the 10 week programme (Pyramid group) and a non-intervention comparison group. Club leaders (n = 23) were trained, Pyramid volunteers. A mixed-methods design was implemented. The Strengths and Difficulties Questionnaire (SDQ), informant-rated version (Goodman, 1997, J Child Psychol Psychiat, 38, 581) and self-report version (Goodman, Meltzer, & Bailey, 1998, Europ Child Adolesc Psychiatry, 7, 125), was used to measure socio-emotional well-being: pre-club (baseline assessment), post-test (within 2 weeks of programme completion), and at 12-month follow-up (informant-rated version only). Focus groups were conducted separately with Pyramid pupils and Club leaders. Findings from informants and self-reports identified significant improvements for the Pyramid group in total difficulties and on pertinent SDQ subscales (e.g., emotional symptoms and peer relationship problems) at post-test. Improvements were sustained at 12-month follow-up. Comparison pupils demonstrated minimal change over time. Thematic analysis of qualitative data supported the quantitative findings and provided valuable insights into the Pyramid Club experience. Findings contribute to evidence-based, preventative models for the early adolescent population and support the social validity of Pyramid Club. © 2018 The Authors. British Journal of Education Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

Long-term type 1 diabetes alters the deposition of collagens and proteoglycans in the early pregnant myometrium of mice.

PubMed

Favaro, Rodolfo R; Raspantini, Priscila R; Salgado, Renato M; Fortes, Zuleica B; Zorn, Telma M T

2015-04-01

We have previously shown that long-term type 1 diabetes affects the structural organization, contractile apparatus and extracellular matrix (ECM) of the myometrium during early pregnancy in mice. This study aimed to identify which myometrial ECM components are affected by diabetes, including fibril-forming collagen types I, III and V, as well as proteoglycans, decorin, lumican, fibromodulin and biglycan. Alloxan-induced type 1 diabetic female mice were divided into subgroups D1 and D2, formed by females that bred 90-100 and 100-110 days after diabetes induction, respectively. The deposition of ECM components in the myometrium was evaluated by immunohistochemistry/immunofluorescence. The subgroup D1 showed decreased deposition of collagen types I and III in the external muscle layer (EML) and decreased collagen types III and V in the internal muscle layer (IML). Collagen types I and III were decreased in both muscle layers of the subgroup D2. In addition, increased deposition of collagen types I and III and lumican as well as decreased collagen type V were observed in the connective tissue between muscle layers of D2. Lumican was decreased in the EML of the subgroups D1 and D2. Fibromodulin was repressed in the IML and EML of both D1 and D2. In contrast, decorin deposition diminished only in muscle layers of D2. No changes were noticed for biglycan. Subgroups D1 and D2 showed distinct stages of progression of diabetic complications in the myometrium, characterized by both common and specific sets of changes in the ECM composition.

An Investigation into III-V Compounds to Reach 20% Efficiency with Minimum Cell Thickness in Ultrathin-Film Solar Cells

NASA Astrophysics Data System (ADS)

Haque, K. A. S. M. Ehteshamul; Galib, Md. Mehedi Hassan

2013-10-01

III-V single-junction solar cells have already achieved very high efficiency levels. However, their use in terrestrial applications is limited by the high fabrication cost. High-efficiency, ultrathin-film solar cells can effectively solve this problem, as their material requirement is minimum. This work presents a comparison among several III-V compounds that have high optical absorption capability as well as optimum bandgap (around 1.4 eV) for use as solar cell absorbers. The aim is to observe and compare the ability of these materials to reach a target efficiency level of 20% with minimum possible cell thickness. The solar cell considered has an n-type ZnSe window layer, an n-type Al0.1Ga0.9As emitter layer, and a p-type Ga0.5In0.5P back surface field (BSF) layer. Ge is used as the substrate. In the initial design, a p-type InP base was sandwiched between the emitter and the BSF layer, and the design parameters for the device were optimized by analyzing the simulation outcomes with ADEPT/F, a one-dimensional (1D) simulation tool. Then, the minimum cell thickness that achieves 20% efficiency was determined by observing the efficiency variation with cell thickness. Afterwards, the base material was changed to a few other selected III-V compounds, and for each case, the minimum cell thickness was determined in a similar manner. Finally, these cell thickness values were compared and analyzed to identify more effective base layer materials for III-V single-junction solar cells.

Characterization of microbially Fe(III)-reduced nontronite: Environmental cell-transmission electron microscopy study

USGS Publications Warehouse

Kim, Jin-wook; Furukawa, Yoko; Daulton, Tyrone L.; Lavoie, Dawn L.; Newell, Steven W.

2003-01-01

Microstructural changes induced by the microbial reduction of Fe(III) in nontronite by Shewanella oneidensis were studied using environmental cell (EC)-transmission electron microscopy (TEM), conventional TEM, and X-ray powder diffraction (XRD). Direct observations of clays by EC-TEM in their hydrated state allowed for the first time an accurate and unambiguous TEM measurement of basal layer spacings and the contraction of layer spacing caused by microbial effects, most likely those of Fe(III) reduction. Non-reduced and Fe(III)-reduced nontronite, observed by EC-TEM, exhibited fringes with mean d001 spacings of 1.50 nm (standard deviation, σ = 0.08 nm) and 1.26 nm (σ = 0.10 nm), respectively. In comparison, the same samples embedded with Nanoplast resin, sectioned by microtome, and observed using conventional TEM, displayed layer spacings of 1.0–1.1 nm (non-reduced) and 1.0 nm (reduced). The results from Nanoplast-embedded samples are typical of conventional TEM studies, which have measured nearly identical layer spacings regardless of Fe oxidation state. Following Fe(III) reduction, both EC- and conventional TEM showed an increase in the order of nontronite selected area electron diffraction patterns while the images exhibited fewer wavy fringes and fewer layer terminations. An increase in stacking order in reduced nontronite was also suggested by XRD measurements. In particular, the ratio of the valley to peak intensity (v/p) of the 1.7 nm basal 001 peak of ethylene glycolated nontronite was measured at 0.65 (non-reduced) and 0.85 (microbially reduced).

The New Modern Mediterranean Diet Italian Pyramid.

PubMed

Vitiello, V; Germani, A; Capuzzo Dolcetta, E; Donini, L M; Del Balzo, V

2016-01-01

Epidemiological studies have established the health benefits associated with the adherence to the MD (Mediterranean Diet), mainly in relation to reducing the risk of developing the non communicable diseases. The MD is a sustainable diet model that respects the environment, promotes the bio-diversity, the local cultural heritages, the social interaction and economic aspects. The pyramid is a graphical representation designed to represent the frequencies of consumption and portion sizes of each food according to the Mediterranean model and tradition. The pyramid was developed taking into account the LARN (Reference Intake of nutrients and energy for Italian Population) and the Italian Guidelines for a healthy diet. The frequency of consumption and the portion size recommended are located at the different level of the pyramid. At the base of the pyramid there are the foods that should be consumed every meal and some concepts typical of the Mediterranean culture. In the middle there are foods that should be consumed daily and at the top of the pyramid the foods consumed on a weekly basis. The new modern MD Italian Pyramid is an important tool to promote the MD and improve the adherence to the MD dietary pattern.

Pyramided rice lines harbouring Allium sativum (asal) and Galanthus nivalis (gna) lectin genes impart enhanced resistance against major sap-sucking pests.

PubMed

Bharathi, Y; Vijaya Kumar, S; Pasalu, I C; Balachandran, S M; Reddy, V D; Rao, K V

2011-03-20

We have developed transgene pyramided rice lines, endowed with enhanced resistance to major sap-sucking insects, through sexual crosses made between two stable transgenic rice lines containing Allium sativum (asal) and Galanthus nivalis (gna) lectin genes. Presence and expression of asal and gna genes in pyramided lines were confirmed by PCR and western blot analyses. Segregation analysis of F₂ progenies disclosed digenic (9:3:3:1) inheritance of the transgenes. Homozygous F₃ plants carrying asal and gna genes were identified employing genetic and molecular methods besides insect bioassays. Pyramided lines, infested with brown planthopper (BPH), green leafhopper (GLH) and whitebacked planthopper (WBPH), proved more effective in reducing insect survival, fecundity, feeding ability besides delayed development of insects as compared to the parental transgenics. Under infested conditions, pyramided lines were found superior to the parental transgenics in their seed yield potential. This study represents first report on pyramiding of two lectin genes into rice exhibiting enhanced resistance against major sucking pests. The pyramided lines appear promising and might serve as a novel genetic resource in rice breeding aimed at durable and broad based resistance against hoppers. Copyright © 2011 Elsevier B.V. All rights reserved.

Semipolar III-nitride laser diodes with zinc oxide cladding.

PubMed

Myzaferi, Anisa; Reading, Arthur H; Farrell, Robert M; Cohen, Daniel A; Nakamura, Shuji; DenBaars, Steven P

2017-07-24

Incorporating transparent conducting oxide (TCO) top cladding layers into III-nitride laser diodes (LDs) improves device design by reducing the growth time and temperature of the p-type layers. We investigate using ZnO instead of ITO as the top cladding TCO of a semipolar (202¯1) III-nitride LD. Numerical modeling indicates that replacing ITO with ZnO reduces the internal loss in a TCO clad LD due to the lower optical absorption in ZnO. Lasing was achieved at 453 nm with a threshold current density of 8.6 kA/cm 2 and a threshold voltage of 10.3 V in a semipolar (202¯1) III-nitride LD with ZnO top cladding.

Mineral resources and resource potential map of the Pyramid Peak Roadless Area, Riverside County, California

USGS Publications Warehouse

Calzia, J.P.

1988-01-01

Geologic and geochemical data indicate that the study area has high resource potential for marble, and moderate resource potential for epithermal gold deposits and tungsten skarns. The Desert Divide Group and the Palm Canyon Complex contain large resources of marble quarried for Portland cement and for construction applications. Gold occurs in quartz veins and pegmatites in the Desert Divide Group and the Penrod Quartz Monzonite. Skarns in the Desert Divide Group contain scheelite and anomalous concentrations of arsenic and beryllium. Thin layers of tremolite asbestos along low-angle thrust faults occur outside of the study area.

Efficient Retrieval of Massive Ocean Remote Sensing Images via a Cloud-Based Mean-Shift Algorithm.

PubMed

Yang, Mengzhao; Song, Wei; Mei, Haibin

2017-07-23

The rapid development of remote sensing (RS) technology has resulted in the proliferation of high-resolution images. There are challenges involved in not only storing large volumes of RS images but also in rapidly retrieving the images for ocean disaster analysis such as for storm surges and typhoon warnings. In this paper, we present an efficient retrieval of massive ocean RS images via a Cloud-based mean-shift algorithm. Distributed construction method via the pyramid model is proposed based on the maximum hierarchical layer algorithm and used to realize efficient storage structure of RS images on the Cloud platform. We achieve high-performance processing of massive RS images in the Hadoop system. Based on the pyramid Hadoop distributed file system (HDFS) storage method, an improved mean-shift algorithm for RS image retrieval is presented by fusion with the canopy algorithm via Hadoop MapReduce programming. The results show that the new method can achieve better performance for data storage than HDFS alone and WebGIS-based HDFS. Speedup and scaleup are very close to linear changes with an increase of RS images, which proves that image retrieval using our method is efficient.

Efficient Retrieval of Massive Ocean Remote Sensing Images via a Cloud-Based Mean-Shift Algorithm

PubMed Central

Song, Wei; Mei, Haibin

2017-01-01

The rapid development of remote sensing (RS) technology has resulted in the proliferation of high-resolution images. There are challenges involved in not only storing large volumes of RS images but also in rapidly retrieving the images for ocean disaster analysis such as for storm surges and typhoon warnings. In this paper, we present an efficient retrieval of massive ocean RS images via a Cloud-based mean-shift algorithm. Distributed construction method via the pyramid model is proposed based on the maximum hierarchical layer algorithm and used to realize efficient storage structure of RS images on the Cloud platform. We achieve high-performance processing of massive RS images in the Hadoop system. Based on the pyramid Hadoop distributed file system (HDFS) storage method, an improved mean-shift algorithm for RS image retrieval is presented by fusion with the canopy algorithm via Hadoop MapReduce programming. The results show that the new method can achieve better performance for data storage than HDFS alone and WebGIS-based HDFS. Speedup and scaleup are very close to linear changes with an increase of RS images, which proves that image retrieval using our method is efficient. PMID:28737699

Kv1 channels control spike threshold dynamics and spike timing in cortical pyramidal neurones

PubMed Central

Higgs, Matthew H; Spain, William J

2011-01-01

Abstract Previous studies showed that cortical pyramidal neurones (PNs) have a dynamic spike threshold that functions as a high-pass filter, enhancing spike timing in response to high-frequency input. While it is commonly assumed that Na+ channel inactivation is the primary mechanism of threshold accommodation, the possible role of K+ channel activation in fast threshold changes has not been well characterized. The present study tested the hypothesis that low-voltage activated Kv1 channels affect threshold dynamics in layer 2–3 PNs, using α-dendrotoxin (DTX) or 4-aminopyridine (4-AP) to block these conductances. We found that Kv1 blockade reduced the dynamic changes of spike threshold in response to a variety of stimuli, including stimulus-evoked synaptic input, current steps and ramps of varied duration, and noise. Analysis of the responses to noise showed that Kv1 channels increased the coherence of spike output with high-frequency components of the stimulus. A simple model demonstrates that a dynamic spike threshold can account for this effect. Our results show that the Kv1 conductance is a major mechanism that contributes to the dynamic spike threshold and precise spike timing of cortical PNs. PMID:21911608

Presque Isle Peninsula, Frie, Pennsylvania. Volume II. Appendices. Revised.

DTIC Science & Technology

1980-11-01

Population Pyramid 9 c. Employment 9 d. Labor Force 9 .e. Public Facilities and Services 14 1. Transportation 14 2. Health Facilities. 14 3. Communications 14...Distribution of Shoreline Use and Overship, 3 Erie County, PA B2 Population Pyramid of Erie County 13 53 Travel Demand Curve Peak Day Good Weather 38...are also experiencing a decline in total population. 4(5) Population Pyramid B2.13 Figure B2, the population pyramid of Erie County, PA, for the years

Computational modeling of direct neuronal recruitment during intracortical microstimulation in somatosensory cortex.

PubMed

Overstreet, C K; Klein, J D; Helms Tillery, S I

2013-12-01

Electrical stimulation of cortical tissue could be used to deliver sensory information as part of a neuroprosthetic device, but current control of the location, resolution, quality, and intensity of sensations elicited by intracortical microstimulation (ICMS) remains inadequate for this purpose. One major obstacle to resolving this problem is the poor understanding of the neural activity induced by ICMS. Even with new imaging methods, quantifying the activity of many individual neurons within cortex is difficult. We used computational modeling to examine the response of somatosensory cortex to ICMS. We modeled the axonal arbors of eight distinct morphologies of interneurons and seven types of pyramidal neurons found in somatosensory cortex and identified their responses to extracellular stimulation. We then combined these axonal elements to form a multi-layered slab of simulated cortex and investigated the patterns of neural activity directly induced by ICMS. Specifically we estimated the number, location, and variety of neurons directly recruited by stimulation on a single penetrating microelectrode. The population of neurons activated by ICMS was dependent on both stimulation strength and the depth of the electrode within cortex. Strikingly, stimulation recruited interneurons and pyramidal neurons in very different patterns. Interneurons are primarily recruited within a dense, continuous region around the electrode, while pyramidal neurons were recruited in a sparse fashion both near the electrode and up to several millimeters away. Thus ICMS can lead to an unexpectedly complex spatial distribution of firing neurons. These results lend new insights to the complexity and range of neural activity that can be induced by ICMS. This work also suggests mechanisms potentially responsible for the inconsistency and unnatural quality of sensations initiated by ICMS. Understanding these mechanisms will aid in the design of stimulation that can be used to generate effective sensory feedback for neuroprosthetic devices.

Postsynaptic FMRP Promotes the Pruning of Cell-to-Cell Connections among Pyramidal Neurons in the L5A Neocortical Network

PubMed Central

Patel, Ankur B.; Loerwald, Kristofer W.; Huber, Kimberly M.

2014-01-01

Pruning of structural synapses occurs with development and learning. A deficit in pruning of cortical excitatory synapses and the resulting hyperconnectivity is hypothesized to underlie the etiology of fragile X syndrome (FXS) and related autistic disorders. However, clear evidence for pruning in neocortex and its impairment in FXS remains elusive. Using simultaneous recordings of pyramidal neurons in the layer 5A neocortical network of the wild-type (WT) mouse to observe cell-to-cell connections in isolation, we demonstrate here a specific form of “connection pruning.” Connection frequency among pyramidal neurons decreases between the third and fifth postnatal weeks, indicating a period of connection pruning. Over the same interval in the FXS model mouse, the Fmr1 knock-out (KO), connection frequency does not decrease. Therefore, connection frequency in the fifth week is higher in the Fmr1 KO compared with WT, indicating a state of hyperconnectivity. These alterations are due to postsynaptic deletion of Fmr1. At early ages (2 weeks), postsynaptic Fmr1 promoted the maturation of cell-to-cell connections, but not their number. These findings indicate that impaired connection pruning at later ages, and not an excess of connection formation, underlies the hyperconnectivity in the Fmr1 KO mouse. FMRP did not appear to regulate synapses individually, but instead regulated cell-to-cell connectivity in which groups of synapses mediating a single cell-to-cell connection are uniformly removed, retained, and matured. Although we do not link connection pruning directly to the pruning of structurally defined synapses, this study nevertheless provides an important model system for studying altered pruning in FXS. PMID:24573297

Postsynaptic FMRP promotes the pruning of cell-to-cell connections among pyramidal neurons in the L5A neocortical network.

PubMed

Patel, Ankur B; Loerwald, Kristofer W; Huber, Kimberly M; Gibson, Jay R

2014-02-26

Pruning of structural synapses occurs with development and learning. A deficit in pruning of cortical excitatory synapses and the resulting hyperconnectivity is hypothesized to underlie the etiology of fragile X syndrome (FXS) and related autistic disorders. However, clear evidence for pruning in neocortex and its impairment in FXS remains elusive. Using simultaneous recordings of pyramidal neurons in the layer 5A neocortical network of the wild-type (WT) mouse to observe cell-to-cell connections in isolation, we demonstrate here a specific form of "connection pruning." Connection frequency among pyramidal neurons decreases between the third and fifth postnatal weeks, indicating a period of connection pruning. Over the same interval in the FXS model mouse, the Fmr1 knock-out (KO), connection frequency does not decrease. Therefore, connection frequency in the fifth week is higher in the Fmr1 KO compared with WT, indicating a state of hyperconnectivity. These alterations are due to postsynaptic deletion of Fmr1. At early ages (2 weeks), postsynaptic Fmr1 promoted the maturation of cell-to-cell connections, but not their number. These findings indicate that impaired connection pruning at later ages, and not an excess of connection formation, underlies the hyperconnectivity in the Fmr1 KO mouse. FMRP did not appear to regulate synapses individually, but instead regulated cell-to-cell connectivity in which groups of synapses mediating a single cell-to-cell connection are uniformly removed, retained, and matured. Although we do not link connection pruning directly to the pruning of structurally defined synapses, this study nevertheless provides an important model system for studying altered pruning in FXS.

Influence of highly distinctive structural properties on the excitability of pyramidal neurons in monkey visual and prefrontal cortices

PubMed Central

Amatrudo, Joseph M.; Weaver, Christina M.; Crimins, Johanna L.; Hof, Patrick R.; Rosene, Douglas L.; Luebke, Jennifer I.

2012-01-01

Whole-cell patch-clamp recordings and high-resolution 3D morphometric analyses of layer 3 pyramidal neurons in in vitro slices of monkey primary visual cortex (V1) and dorsolateral granular prefrontal cortex (dlPFC) revealed that neurons in these two brain areas possess highly distinctive structural and functional properties. Area V1 pyramidal neurons are much smaller than dlPFC neurons, with significantly less extensive dendritic arbors and far fewer dendritic spines. Relative to dlPFC neurons, V1 neurons have a significantly higher input resistance, depolarized resting membrane potential and higher action potential (AP) firing rates. Most V1 neurons exhibit both phasic and regular-spiking tonic AP firing patterns, while dlPFC neurons exhibit only tonic firing. Spontaneous postsynaptic currents are lower in amplitude and have faster kinetics in V1 than in dlPFC neurons, but are no different in frequency. Three-dimensional reconstructions of V1 and dlPFC neurons were incorporated into computational models containing Hodgkin-Huxley and AMPA- and GABAA-receptor gated channels. Morphology alone largely accounted for observed passive physiological properties, but led to AP firing rates that differed more than observed empirically, and to synaptic responses that opposed empirical results. Accordingly, modeling predicts that active channel conductances differ between V1 and dlPFC neurons. The unique features of V1 and dlPFC neurons are likely fundamental determinants of area-specific network behavior. The compact electrotonic arbor and increased excitability of V1 neurons support the rapid signal integration required for early processing of visual information. The greater connectivity and dendritic complexity of dlPFC neurons likely support higher level cognitive functions including working memory and planning. PMID:23035077

Understanding socio-economic inequalities in food choice behaviour: can Maslow's pyramid help?

PubMed

van Lenthe, Frank J; Jansen, Tessa; Kamphuis, Carlijn B M

2015-04-14

Socio-economic groups differ in their material, living, working and social circumstances, which may result in different priorities about their daily-life needs, including the priority to make healthy food choices. Following Maslow's hierarchy of human needs, we hypothesised that socio-economic inequalities in healthy food choices can be explained by differences in the levels of need fulfilment. Postal survey data collected in 2011 (67·2 % response) from 2903 participants aged 20-75 years in the Dutch GLOBE (Gezondheid en Levens Omstandigheden Bevolking Eindhoven en omstreken) study were analysed. Maslow's hierarchy of human needs (measured with the Basic Need Satisfaction Inventory) was added to age- and sex-adjusted linear regression models that linked education and net household income levels to healthy food choices (measured by a FFQ). Most participants (38·6 %) were in the self-actualisation layer of the pyramid. This proportion was highest among the highest education group (47·6 %). Being in a higher level of the hierarchy was associated with a higher consumption of fruits and vegetables as well as more healthy than unhealthy bread, snack and dairy consumption. Educational inequalities in fruit and vegetable intake (B= -1·79, 95 % CI -2·31, -1·28 in the lowest education group) were most reduced after the hierarchy of needs score was included (B= -1·57, 95 % CI - ·09, -1·05). Inequalities in other healthy food choices hardly changed after the hierarchy of needs score was included. People who are satisfied with higher-level needs make healthier food choices. Studies aimed at understanding socio-economic inequalities in food choice behaviour need to take differences in the priority given to daily-life needs by different socio-economic groups into account, but Maslow's pyramid offers little help.

Involvement of pre- and postsynaptic NMDA receptors at local circuit interneuron connections in rat neocortex

PubMed Central

De-May, C.L.; Ali, A.B.

2013-01-01

To investigate the involvement of N-Methyl-D-aspartate (NMDA) receptors in local neocortical synaptic transmission, dual whole-cell recordings – combined with biocytin labelling – were obtained from bitufted adapting, multipolar adapting or multipolar non-adapting interneurons and pyramidal cells in layers II–V of rat (postnatal days 17–22) sensorimotor cortex. The voltage dependency of the amplitude of Excitatory postsynaptic potentials (EPSPs) received by the three types of interneuron appeared to coincide with the interneuron subclass; upon depolarisation, EPSPs received by multipolar non-adapting interneurons either decreased in amplitude or appeared insensitive, multipolar adapting interneuron EPSP amplitudes increased or appeared insensitive, whereas bitufted interneuron EPSP amplitudes increased or decreased. Connections were challenged with the NMDA receptor antagonist d-(−)-2-amino-5-phosphonopentanoic acid (d-AP5) (50 μM) revealing NMDA receptors to contribute to EPSPs received by all cell types, this also abolished the non-conventional voltage dependency. Reciprocal connections were frequent between pyramidal cells and multipolar interneurons, and inhibitory postsynaptic potentials (IPSPs) elicited in pyramidal cells by both multipolar adapting and multipolar non-adapting interneurons were sensitive to a significant reduction in amplitude by d-AP5. The involvement of presynaptic NMDA receptors was indicated by coefficient of variation analysis and an increase in the failures of transmission. Furthermore, by loading MK-801 into the pre- or postsynaptic neurons, we observed that a reduction in inhibition requires presynaptic and not postsynaptic NMDA receptors. These results suggest that NMDA receptors possess pre- and postsynaptic roles at selective neocortical synapses that are probably important in governing spike-timing and information flow. PMID:23079623

Outward current produced by somatostatin (SRIF) in rat anterior cingulate pyramidal cells in vitro

PubMed Central

Hicks, G A; Feniuk, W; Humphrey, P P A

1998-01-01

A high density of receptors for somatostatin (SRIF) exists in the anterior cingulate cortex but their function is unknown. Whole-cell patch clamp recordings were made from visualized deep layer pyramidal cells of the rat anterior cingulate cortex contained in isolated brain slices to investigate the putative effects of SRIF and to identify the receptor subtype(s) involved.SRIF (1–1000 nM) produced a concentration-dependent outward current which was associated with an increased membrane conductance, was sensitive to Ba2+ (300 μM–1 mM), and was absent in the presence of a maximal concentration of the GABAB receptor agonist, baclofen (100 μM). These observations suggest the outward current was carried by K+ ions.SRIF analogues also elicited outward currents with a rank potency order of (EC50, nM): octreotide (1.8)>BIM-23027 (3.7)>SRIF (20)=L-362,855 (20). BIM-23056 was without agonist or antagonist activity. Responses to L-362,855 were unlike those to the other agonists since they were sustained for the duration of the application.The sst2 receptor antagonist, L-Tyr8Cyanamid 154806 (1 μM), had no effect alone but partially reversed responses to submaximal concentrations of SRIF (100 nM, 44±6% reversal) and L-362,855 (100 nM, 70±6% reversal) and fully reversed the response to BIM-23027 (10 nM). In contrast, L-Tyr8Cyanamid 154806 did not antagonize the response to baclofen (10 μM).We conclude that SRIF activates a K+ conductance in anterior cingulate pyramidal neurones via an action predominantly at sst2 receptors. PMID:9630367

Ternary AlGaN Alloys with High Al Content and Enhanced Compositional Homogeneity Grown by Plasma-Assisted Molecular Beam Epitaxy

NASA Astrophysics Data System (ADS)

Fellmann, Vincent; Jaffrennou, Périne; Sam-Giao, Diane; Gayral, Bruno; Lorenz, Katharina; Alves, Eduardo; Daudin, Bruno

2011-03-01

We have studied the influence of III/N flux ratio and growth temperature on structural and optical properties of high Al-content, around 50-60%, AlGaN alloy layers grown by plasma-assisted molecular beam epitaxy. In a first part, based on structural analysis by Rutherford Backscattering Spectroscopy, we establish that a III/N flux ratio slightly above 1 produces layers with low amount of structural defects. In a second part, we study the effect of growth temperature on structural and optical properties of layers grown with previously determined optimal III/N flux ratio. We find that optimal growth temperatures for Al0.50Ga0.50N layers with compositional homogeneity related with narrow UV photoluminescence properties are in the low temperature range for growing GaN layers, i.e., 650-680 °C. We propose that lowering Ga adatom diffusion on the surface favors random incorporation of both Ga and Al adatoms on wurtzite crystallographic sites leading to the formation of an homogeneous alloy.

Stable Density and Dynamics of Dendritic Spines of Cortical Neurons Across the Estrous Cycle While Expressing Differential Levels of Sensory-Evoked Plasticity.

PubMed

Alexander, Bailin H; Barnes, Heather M; Trimmer, Emma; Davidson, Andrew M; Ogola, Benard O; Lindsey, Sarah H; Mostany, Ricardo

2018-01-01

Periodic oscillations of gonadal hormone levels during the estrous cycle exert effects on the female brain, impacting cognition and behavior. While previous research suggests that changes in hormone levels across the cycle affect dendritic spine dynamics in the hippocampus, little is known about the effects on cortical dendritic spines and previous studies showed contradictory results. In this in vivo imaging study, we investigated the impact of the estrous cycle on the density and dynamics of dendritic spines of pyramidal neurons in the primary somatosensory cortex of mice. We also examined if the induction of synaptic plasticity during proestrus, estrus, and metestrus/diestrus had differential effects on the degree of remodeling of synapses in this brain area. We used chronic two-photon excitation (2PE) microscopy during steady-state conditions and after evoking synaptic plasticity by whisker stimulation at the different stages of the cycle. We imaged apical dendritic tufts of layer 5 pyramidal neurons of naturally cycling virgin young female mice. Spine density, turnover rate (TOR), survival fraction, morphology, and volume of mushroom spines remained unaltered across the estrous cycle, and the values of these parameters were comparable with those of young male mice. However, while whisker stimulation of female mice during proestrus and estrus resulted in increases in the TOR of spines (74.2 ± 14.9% and 75.1 ± 12.7% vs. baseline, respectively), sensory-evoked plasticity was significantly lower during metestrus/diestrus (32.3 ± 12.8%). In males, whisker stimulation produced 46.5 ± 20% increase in TOR compared with baseline-not significantly different from female mice at any stage of the cycle. These results indicate that, while steady-state density and dynamics of dendritic spines of layer 5 pyramidal neurons in the primary somatosensory cortex of female mice are constant during the estrous cycle, the susceptibility of these neurons to sensory-evoked structural plasticity may be dependent on the stage of the cycle. Since dendritic spines are more plastic during proestrus and estrus than during metestrus/diestrus, certain stages of the cycle could be more suitable for forms of memory requiring de novo formation and elimination of spines and other stages for forms of memory where retention and/or repurposing of already existing synaptic connections is more pertinent.

The underside of the cerebral cortex: layer V/VI spiny inverted neurons

PubMed Central

Mendizabal-Zubiaga, Juan L; Reblet, Concepcion; Bueno-Lopez, Jose L

2007-01-01

This paper presents an account of past and current research on spiny inverted neurons – alternatively also known as ‘inverted pyramidal neurons’– in rats, rabbits and cats. In our laboratory, we have studied these cells with a battery of techniques suited for light and electron microscopy, including Nissl staining, Golgi impregnation, dye intracellular filling and axon retrograde track-tracing. Our results show that spiny inverted neurons make up less than 8.5 and 5.5% of all cortical neurons in the primary and secondary rabbit visual cortex, respectively. Infragranular spiny inverted neurons constitute 15 and 8.5% of infragranular neurons in the same animal and areas. Spiny inverted neurons congregate at layers V–VI in all studied species. Studies have also revealed that spiny inverted neurons are excitatory neurons which furnish axons for various cortico-cortical, cortico-claustral and cortico-striatal projections, but not for non-telencephalic centres such as the lateral and medial geniculate nuclei, the colliculi or the pons. As a group, each subset of inverted cells contributing to a given projection is located below the pyramidal neurons whose axons furnish the same centre. Spiny inverted neurons are particularly conspicuous as a source of the backward cortico-cortical projection to primary visual cortex and from this to the claustrum. Indeed, they constitute up to 82% of the infragranular cells that furnish these projections. Spiny inverted neurons may be classified into three subtypes according to the point of origin of the axon on the cell: the somatic basal pole which faces the cortical outer surface, the somatic flank and the reverse apical dendrite. As seen with electron microscopy, the axon initial segments of these subtypes are distinct from one another, not only in length and thickness, but also in the number of received synaptic boutons. All of these anatomical features together may support a synaptic-input integration which is peculiar to spiny inverted neurons. In this way, two differently qualified streams of axonal output may coexist in a projection which arises from a particular infragranular point within a given cortical area; one stream would be furnished by the typical pyramidal neurons, whereas spiny inverted neurons would constitute the other source of distinct information flow. PMID:17635629

Stable Density and Dynamics of Dendritic Spines of Cortical Neurons Across the Estrous Cycle While Expressing Differential Levels of Sensory-Evoked Plasticity

PubMed Central

Alexander, Bailin H.; Barnes, Heather M.; Trimmer, Emma; Davidson, Andrew M.; Ogola, Benard O.; Lindsey, Sarah H.; Mostany, Ricardo

2018-01-01

Periodic oscillations of gonadal hormone levels during the estrous cycle exert effects on the female brain, impacting cognition and behavior. While previous research suggests that changes in hormone levels across the cycle affect dendritic spine dynamics in the hippocampus, little is known about the effects on cortical dendritic spines and previous studies showed contradictory results. In this in vivo imaging study, we investigated the impact of the estrous cycle on the density and dynamics of dendritic spines of pyramidal neurons in the primary somatosensory cortex of mice. We also examined if the induction of synaptic plasticity during proestrus, estrus, and metestrus/diestrus had differential effects on the degree of remodeling of synapses in this brain area. We used chronic two-photon excitation (2PE) microscopy during steady-state conditions and after evoking synaptic plasticity by whisker stimulation at the different stages of the cycle. We imaged apical dendritic tufts of layer 5 pyramidal neurons of naturally cycling virgin young female mice. Spine density, turnover rate (TOR), survival fraction, morphology, and volume of mushroom spines remained unaltered across the estrous cycle, and the values of these parameters were comparable with those of young male mice. However, while whisker stimulation of female mice during proestrus and estrus resulted in increases in the TOR of spines (74.2 ± 14.9% and 75.1 ± 12.7% vs. baseline, respectively), sensory-evoked plasticity was significantly lower during metestrus/diestrus (32.3 ± 12.8%). In males, whisker stimulation produced 46.5 ± 20% increase in TOR compared with baseline—not significantly different from female mice at any stage of the cycle. These results indicate that, while steady-state density and dynamics of dendritic spines of layer 5 pyramidal neurons in the primary somatosensory cortex of female mice are constant during the estrous cycle, the susceptibility of these neurons to sensory-evoked structural plasticity may be dependent on the stage of the cycle. Since dendritic spines are more plastic during proestrus and estrus than during metestrus/diestrus, certain stages of the cycle could be more suitable for forms of memory requiring de novo formation and elimination of spines and other stages for forms of memory where retention and/or repurposing of already existing synaptic connections is more pertinent. PMID:29615867

A multi-focus image fusion method via region mosaicking on Laplacian pyramids

PubMed Central

Kou, Liang; Zhang, Liguo; Sun, Jianguo; Han, Qilong; Jin, Zilong

2018-01-01

In this paper, a method named Region Mosaicking on Laplacian Pyramids (RMLP) is proposed to fuse multi-focus images that is captured by microscope. First, the Sum-Modified-Laplacian is applied to measure the focus of multi-focus images. Then the density-based region growing algorithm is utilized to segment the focused region mask of each image. Finally, the mask is decomposed into a mask pyramid to supervise region mosaicking on a Laplacian pyramid. The region level pyramid keeps more original information than the pixel level. The experiment results show that RMLP has best performance in quantitative comparison with other methods. In addition, RMLP is insensitive to noise and can reduces the color distortion of the fused images on two datasets. PMID:29771912

Cathodic stripping voltammetry of nickel: sonoelectrochemical exploitation of the Ni(III)/Ni(II) couple.

PubMed

Davis, James; Vaughan, D Huw; Stirling, David; Nei, Lembit; Compton, Richard G

2002-07-19

The exploitation of the Ni(III)/Ni(II) transition as a means of quantifying the concentration of nickel within industrial samples was assessed. The methodology relies upon the reagentless electrodeposition of Ni onto a glassy carbon electrode and the subsequent oxidative conversion of the metallic layer to Ni(III). The analytical signal is derived from a cathodic stripping protocol in which the reduction of the Ni(III) layer to Ni(II) is monitored through the use of square wave voltammetry. The procedure was refined through the introduction of an ultrasonic source which served to both enhance the deposition of nickel and to remove the nickel hydroxide layer that results from the measurement process. A well-defined stripping peak was observed at +0.7 V (vs. Agmid R:AgCl) with the response found to be linear over the range 50 nM to 1 muM (based on a 30 s deposition time). Other metal ions such as Cu(II), Mn(II), Cr(III), Pb(II), Cd(II), Zn(II), Fe(III) and Co(II) did not interfere with the response when present in hundred fold excess. The viability of the technique was evaluated through the determination of nickel within a commercial copper nickel alloy and validated through an independent comparison with a standard ICP-AES protocol.

catena-Poly[[[tetra­kis(μ-2-butenoato)dicopper(II)]-μ-2-butenoato-[diaqua­(2-butenoato)holmium(III)]-di-μ-2-butenoato-[diaqua­(2-butenoato)holmium(III)]-μ-2-butenoato] trihydrate

PubMed Central

Perec, Mireille; Garland, Maria Teresa; Baggio, Ricardo

2008-01-01

The title compound {[Cu2Ho2(C4H5O2)10(H2O)4]·3H2O}n, is a one-dimensional 3d/4f organic–inorganic hybrid complex, the HoIII member of the isotypic lanthanoid series with Ln = GdIII, ErIII and YIII. The structure shows an alternation of Cu2 and Ho2 dinuclear units bridged by the ligands and hydrogen bonds only. The chains are composed of Cu2 classical dinuclear η1:η1:μ2 fourfold bridges [Cu⋯Cu = 2.6417 (9) Å] and of Ho2 units bridged by two η2:η1:μ2 carboxyl­ate units. This results in distorted square-based pyramidal CuO5 units and irregular HoO9 units. The alternating Cu2 and Ho2 units are bridged into linear arrays along the a axis by a set of one η2:η1:μ2 carboxyl­ate O atom and two hydrogen bonds with Cu⋯Ho separations of 4.4883 (10) and 4.5086 (10) Å. The distance between adjacent chains, as calculated by the closest and furthest distances between two chains, covers the range 10–14 Å. The H atoms of the water mol­ecules could not be located, but the O⋯O separations for these species suggest the presence of O—H⋯O hydrogen bonds. PMID:21580901

Earth Observation

NASA Image and Video Library

2012-07-25

ISS032-E-009123 (26 July 2012) --- Pyramids at Giza, Egypt are featured in this image photographed by an Expedition 32 crew member on the International Space Station. The Great Pyramids at Giza (center) are the last of the Seven Wonders of the Ancient World, and are perhaps the most famous of the ancient monuments in the Nile River Delta region of Egypt. They are also a favorite subject of photography from orbit ? particularly when high resolution imagery can be obtained. The southeast-facing sides of the pyramids of the pharaohs Khufu, Khafre, and Menkaure are all brightly illuminated by the sun, while the northwest facing sides are in shadow. This shadowing also highlights smaller unfinished pyramids to the south of Menkaure?s pyramid, as well as fields of rectangular flat roofed mastabas (tombs) to the east and west of Khufu?s pyramid. While not as grand as the pyramids, mastabas were the burial places of prominent persons during the periods of the ancient pharaohs. To the southeast of Khufu?s pyramid, the head and rear haunches of the Sphinx are also visible (albeit not clearly). It is a short distance between the glories of ancient Egypt and the modern Cairo metropolitan area to the north and east. The green vegetation of a hotel golf course (center left), and the numerous building and streets of El Giza, provide stark contrast to the bare rock and soil of the adjacent desert. Roadways visible in the desert (right) connect the urban regions to the east with further development to the north.

Experimental implementation of a Pyramid WFS: Towards the first SCAO systems for E-ELT

NASA Astrophysics Data System (ADS)

Bond, C.; El Hadi, K.; Sauvage, J. F.; Correia, C.; Fauvarque, O.; Rabaud, D.; Neichel, B.; Fusco, T.

2015-12-01

Investigations into the Pyramid wavefront sensor (P-WFS) have experimentally demonstrated the ability to achieve a better performance than with a standard Shack-Hartmann sensor (SH-WFS). Implementation on the Large Binocular Telescope (LBT) provided the first operational demonstration on a facility-class instrument of a P-WFS on sky. The desire to implement a Pyramid on an Extremely Large Telescope (ELT) requires further characterisation in order to optimise the performance and match our knowledge and understanding of other wave-front sensors (WFSs). Within the framework of the European Extremely Large Telescope (E-ELT), the Laboratoire d'Astrophysique de Marseille (LAM) is involved in the preparation of the Single Conjugate Adaptive Optics (SCAO) system of HARMONI, E-ELT's 1st light integral field spectrograph (IFU). The current baseline WFS for this adaptive optics system is a Pyramid WFS using a high speed and sensitive OCAM2 camera. At LAM we are currently carrying out laboratory demonstrations of a Pyramid-WFS, with the aim to fully characterise the behaviour of the Pyramid in terms of sensitivity and linear range. This will lead to a full operational procedure for the use of the Pyramid on-sky, assisting with current designs and future implementations. The final goal is to provide an on sky comparison between the Pyramid and Shack-Hartmann at Observatoire de la Côte d'Azur (OCA). Here we present our experimental setup and preliminary results.

Clipping polygon faces through a polyhedron of vision

NASA Technical Reports Server (NTRS)

Florence, Judit K. (Inventor); Rohner, Michel A. (Inventor)

1980-01-01

A flight simulator combines flight data and polygon face terrain data to provide a CRT display at each window of the simulated aircraft. The data base specifies the relative position of each vertex of each polygon face therein. Only those terrain faces currently appearing within the pyramid of vision defined by the pilots eye and the edges of the pilots window need be displayed at any given time. As the orientation of the pyramid of vision changes in response to flight data, the displayed faces are correspondingly displaced, eventually moving out of the pyramid of vision. Faces which are currently not visible (outside the pyramid of vision) are clipped from the data flow. In addition, faces which are only partially outside of pyramid of vision are reconstructed to eliminate the outside portion. Window coordinates are generated defining the distance between each vertex and each of the boundary planes forming the pyramid of vision. The sign bit of each window coordinate indicates whether the vertex is on the pyramid of vision side of the associated boundary panel (positive), or on the other side thereof (negative). The set of sign bits accompanying each vertex constitute the outcode of that vertex. The outcodes (O.C.) are systematically processed and examined to determine which faces are completely inside the pyramid of vision (Case A--all signs positive), which faces are completely outside (Case C--All signs negative) and which faces must be reconstructed (Case B--both positive and negative signs).

Seasonal and spatial variation in soil chemistry and anaerobic processes in an Arctic ecosystem

NASA Astrophysics Data System (ADS)

Lipson, D.; Mauritz, M.; Bozzolo, F.; Raab, T. K.; Santos, M. J.; Friedman, E. F.; Rosenbaum, M.; Angenent, L.

2009-12-01

Drained thaw lake basins (DTLB) are the dominant landform in the Arctic coastal plain near Barrow, Alaska. Our previous work in a DTLB showed that Fe(III) and humic substances are important electron acceptors in anaerobic respiration, and play a significant role in the C cycle of these organic-rich soils. In the current study, we investigated seasonal and spatial patterns of availability of electron acceptors and labile substrate, redox conditions and microbial activity. Landscapes within DTLB contain complex, fine-scale topography arising from ice wedge polygons, which produce raised and lowered areas. One goal of our study was to determine the effects of microtopographic variation on the potential for Fe(III) reduction and other anaerobic processes. Additionally, the soil in the study site has a complex vertical structure, with an organic peat layer overlying a mineral layer, overlying permafrost. We described variations in soil chemistry across depth profiles into the permafrost. Finally, we installed an integrated electrode/potentiostat system to electrochemically monitor microbial activity in the soil. Topographically low areas differed from high areas in most of the measured variables: low areas had lower oxidation-reduction potential, higher pH and electrical conductivity. Soil pore water from low areas had higher concentrations of Fe(III), Fe(II), dissolved organic C (DOC), and aromaticity (UV absorbance at 260nm, “A260”). Low areas also had higher concentrations of dissolve CO2 and CH4 in soil pore water. Laboratory incubations of soil showed a trend toward higher potentials for Fe(III) reduction in topographically low areas. Clearly, ice wedge-induced microtopography exerts a strong control on microbial processes in this DTLB landscape, with increased anaerobic activity occurring in the wetter, depressed areas. Soil water extracted from 5-15 cm depth had higher concentrations of Fe(III), Fe(II), A260, and DOC compared to soil water sampled from 0-5cm. The soil depth profile showed highest concentrations of acid-extractable Fe in the mineral layer and permafrost, though Fe(III) was highest in the surface layer. Total and soluble C increased with depth, as did the potential for CO2 and CH4 production in anaerobic incubations. Thus, the mineral layer may be a significant source of Fe for oxidation-reduction reactions that occur at shallower depths, though methanogenesis dominates in the mineral layer, while Fe(III) reduction dominates in the organic layer. Most of the ions measured in the soil pore water (Fe(III), DOC, A260) showed the same general seasonal pattern: high concentrations soon after soils thawed, declining over time until mid-August. Concentrations of Fe(II) in soil pore water were fairly stable over time. There was a significant positive relationship between A260 and Fe(III) concentrations, possibly indicating the presence of microbially-produced aromatic chelating molecules. Potentiostat measurements confirmed the presence of an electrochemically active microbial community in the soil.

Pyramid Lake Renewable Energy Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

John Jackson

2008-03-14

The Pyramid Lake Paiute Tribe is a federally recognized Tribe residing on the Pyramid Lake Reservation in western Nevada. The funding for this project was used to identify blind geothermal systems disconnected from geothermal sacred sites and develop a Tribal energy corporation for evaluating potential economic development for profit.

Single CA3 pyramidal cells trigger sharp waves in vitro by exciting interneurones.

PubMed

Bazelot, Michaël; Teleńczuk, Maria T; Miles, Richard

2016-05-15

The CA3 hippocampal region generates sharp waves (SPW), a population activity associated with neuronal representations. The synaptic mechanisms responsible for the generation of these events still require clarification. Using slices maintained in an interface chamber, we found that the firing of single CA3 pyramidal cells triggers SPW like events at short latencies, similar to those for the induction of firing in interneurons. Multi-electrode records from the CA3 stratum pyramidale showed that pyramidal cells triggered events consisting of putative interneuron spikes followed by field IPSPs. SPW fields consisted of a repetition of these events at intervals of 4-8 ms. Although many properties of induced and spontaneous SPWs were similar, the triggered events tended to be initiated close to the stimulated cell. These data show that the initiation of SPWs in vitro is mediated via pyramidal cell synapses that excite interneurons. They do not indicate why interneuron firing is repeated during a SPW. Sharp waves (SPWs) are a hippocampal population activity that has been linked to neuronal representations. We show that SPWs in the CA3 region of rat hippocampal slices can be triggered by the firing of single pyramidal cells. Single action potentials in almost one-third of pyramidal cells initiated SPWs at latencies of 2-5 ms with probabilities of 0.07-0.76. Initiating pyramidal cells evoked field IPSPs (fIPSPs) at similar latencies when SPWs were not initiated. Similar spatial profiles for fIPSPs and middle components of SPWs suggested that SPW fields reflect repeated fIPSPs. Multiple extracellular records showed that the initiated SPWs tended to start near the stimulated pyramidal cell, whereas spontaneous SPWs could emerge at multiple sites. Single pyramidal cells could initiate two to six field IPSPs with distinct amplitude distributions, typically preceeded by a short-duration extracellular action potential. Comparison of these initiated fields with spontaneously occurring inhibitory field motifs allowed us to identify firing in different interneurones during the spread of SPWs. Propagation away from an initiating pyramidal cell was typically associated with the recruitment of interneurones and field IPSPs that were not activated by the stimulated pyramidal cell. SPW fields initiated by single cells were less variable than spontaneous events, suggesting that more stereotyped neuronal ensembles were activated, although neither the spatial profiles of fields, nor the identities of interneurone firing were identical for initiated events. The effects of single pyramidal cell on network events are thus mediated by different sequences of interneurone firing. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Probable Earthquake Archaeological Effects in the ancient pyramids of Quetzalcóatl and Sun in Teotihuacán (Central Mexico)

NASA Astrophysics Data System (ADS)

Perez-Lopez, Raul; Rodríguez-Pascua, Miguel Angel; Garduño-Monroy, Victor Hugo; Oliveros, Arturo; Giner-Robles, Jorge L.; Silva, Pablo G.

2010-05-01

Teotihuacán was one of the blooming and greater cities of the Prehispanic cultural period within the central valley of México and one of the best archaeological findings of the Earth. During the period of splendour (Middle-Late Classic Period, 350-650 AD), almost 125.000 inhabitants lived in a vast city with more than 2000 stucco and block buildings, including the great religious and ceremonial pyramids: the Great Sun Pyramid, built between 1- 150 AD, the Moon Pyramid, built during a large time span (1-650 AD) and the outstanding Quetzalcóatl Pyramid (Feathered Snake Temple), built in two phases: the first original edifice built before 350 AD and the second one mainly are repairs of the west side and dated post-350 AD. The Quetzalcóatl Pyramid (Q- pyramid) shows a quadrangular base of ca. 3500 m2 with an extraordinary decoration of feathered snakes (attributed to the God Quetzalcóatl) and lizards. The second phase of construction consisted in a townhouse façade covering the west side of the pyramid (post 350AD), up to now with no evidence to justify such annexed wrapper of this west side. This ceremonial building was built within the Citadel, a complex area of Teotihuacán with residential and common zones as well (i.e. market). A detailed view of the steps of the west side stairs, displays different patterns of deformation affecting the blocks of the stair. The original and ancient stair exhibits rotated, overturned and displaced blocks, being stronger this deformation at the base of the pyramid. Moreover, the upper corners of the blocks appear broken in a similar form than the seismic-related feature defined as dipping broken corners or chipped corners. However, the horizontal disposition of the blocks suggests lateral vibration between them from horizontal shaking propagation. Besides, this feature appears lesser evident affecting the lower blocks of the annexed west façade, the only originally preserved ones. We have carried out a systematic measurement of this feature across the original west stairs of the Q- pyramid and the first stair level of the Sun pyramid. Furthermore, these horizontal dipping broken corners were also described affecting the new stairs of the annexed façade of the Q- pyramid. This suggests that seismic shaking could produce that deformation with a relative date of 350 AD post-quem. More data are necessary to properly test the earthquake occurrence and to bracket a probable intensity value.

Structure of thiocyanate hydrolase: a new nitrile hydratase family protein with a novel five-coordinate cobalt(III) center.

PubMed

Arakawa, Takatoshi; Kawano, Yoshiaki; Kataoka, Shingo; Katayama, Yoko; Kamiya, Nobuo; Yohda, Masafumi; Odaka, Masafumi

2007-03-09

Thiocyanate hydrolase (SCNase) of Thiobacillus thioparus THI115 is a cobalt(III)-containing enzyme catalyzing the degradation of thiocyanate to carbonyl sulfide and ammonia. We determined the crystal structures of the apo- and native SCNases at a resolution of 2.0 A. SCNases in both forms had a conserved hetero-dodecameric structure, (alphabetagamma)(4). Four alphabetagamma hetero-trimers were structurally equivalent. One alphabetagamma hetero-trimer was composed of the core domain and the betaN domain, which was located at the center of the molecule and linked the hetero-trimers with novel quaternary interfaces. In both the apo- and native SCNases, the core domain was structurally conserved between those of iron and cobalt-types of nitrile hydratase (NHase). Native SCNase possessed the post-translationally modified cysteine ligands, gammaCys131-SO(2)H and gammaCys133-SOH like NHases. However, the low-spin cobalt(III) was found to be in the distorted square-pyramidal geometry, which had not been reported before in any protein. The size as well as the electrostatic properties of the substrate-binding pocket was totally different from NHases with respect to the charge distribution and the substrate accessibility, which rationally explains the differences in the substrate preference between SCNase and NHase.

Progressive Dictionary Learning with Hierarchical Predictive Structure for Scalable Video Coding.

PubMed

Dai, Wenrui; Shen, Yangmei; Xiong, Hongkai; Jiang, Xiaoqian; Zou, Junni; Taubman, David

2017-04-12

Dictionary learning has emerged as a promising alternative to the conventional hybrid coding framework. However, the rigid structure of sequential training and prediction degrades its performance in scalable video coding. This paper proposes a progressive dictionary learning framework with hierarchical predictive structure for scalable video coding, especially in low bitrate region. For pyramidal layers, sparse representation based on spatio-temporal dictionary is adopted to improve the coding efficiency of enhancement layers (ELs) with a guarantee of reconstruction performance. The overcomplete dictionary is trained to adaptively capture local structures along motion trajectories as well as exploit the correlations between neighboring layers of resolutions. Furthermore, progressive dictionary learning is developed to enable the scalability in temporal domain and restrict the error propagation in a close-loop predictor. Under the hierarchical predictive structure, online learning is leveraged to guarantee the training and prediction performance with an improved convergence rate. To accommodate with the stateof- the-art scalable extension of H.264/AVC and latest HEVC, standardized codec cores are utilized to encode the base and enhancement layers. Experimental results show that the proposed method outperforms the latest SHVC and HEVC simulcast over extensive test sequences with various resolutions.